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<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">As filed with the
Securities and Exchange Commission on February 4, 2005</font></p>

<p align="right" style="margin:0in 0in .0001pt;text-align:right;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">REGISTRATION NO. 333-</font></p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<div style="border:none;border-top:double windowtext 9.0pt;padding:0in 0in 0in 0in;">

<p style="border:none;margin:0in 0in .0001pt;padding:0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

</div>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="5" face="Times New Roman" style="font-size:18.0pt;font-weight:bold;">UNITED
STATES<br>
SECURITIES AND EXCHANGE COMMISSION</font></b></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">WASHINGTON, D.C. 20549</font></b></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<div align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">

<hr size="1" width="25%" noshade color="black" align="center">

</font></div>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="5" face="Times New Roman" style="font-size:18.0pt;font-weight:bold;">FORM S-8</font></b></p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="3" face="Times New Roman" style="font-size:12.0pt;font-weight:bold;">REGISTRATION
STATEMENT</font></b></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="3" face="Times New Roman" style="font-size:12.0pt;font-weight:bold;">under
the</font></b></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="3" face="Times New Roman" style="font-size:12.0pt;font-weight:bold;">SECURITIES
ACT OF 1933</font></b></p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<div align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">

<hr size="1" width="25%" noshade color="black" align="center">

</font></div>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="5" face="Times New Roman" style="font-size:18.0pt;font-weight:bold;">IMMUNOGEN,
INC.</font></b></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(Exact name of Registrant
as specified in its charter)</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<table border="0" cellspacing="0" cellpadding="0" width="100%" style="border-collapse:collapse;width:100.0%;">
 <tr>
  <td width="48%" valign="top" style="padding:0in 0in 0in 0in;width:48.94%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Massachusetts</font></b></p>
  </td>
  <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
  <td width="48%" valign="top" style="padding:0in 0in 0in 0in;width:48.92%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">04-2726691</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="48%" valign="top" style="padding:0in 0in 0in 0in;width:48.94%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(State or other
  jurisdiction</font></p>
  </td>
  <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="48%" valign="top" style="padding:0in 0in 0in 0in;width:48.92%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(I.R.S. Employer</font></p>
  </td>
 </tr>
 <tr>
  <td width="48%" valign="top" style="padding:0in 0in 0in 0in;width:48.94%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">of incorporation or
  organization)</font></p>
  </td>
  <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="48%" valign="top" style="padding:0in 0in 0in 0in;width:48.92%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Identification No.)</font></p>
  </td>
 </tr>
 <tr>
  <td width="48%" valign="top" style="padding:0in 0in 0in 0in;width:48.94%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="48%" valign="top" style="padding:0in 0in 0in 0in;width:48.92%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="100%" colspan="3" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">128 Sidney Street, Cambridge, MA
  02139</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="100%" colspan="3" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">(617)&nbsp;995-2500</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="100%" colspan="3" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(Address of Principal Executive Offices)</font></p>
  </td>
 </tr>
 <tr>
  <td width="48%" valign="top" style="padding:0in 0in 0in 0in;width:48.94%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="48%" valign="top" style="padding:0in 0in 0in 0in;width:48.92%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="100%" colspan="3" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">RESTATED STOCK OPTION PLAN</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="100%" colspan="3" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(Full Title of the Plan)</font></p>
  </td>
 </tr>
 <tr>
  <td width="48%" valign="top" style="padding:0in 0in 0in 0in;width:48.94%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="48%" valign="top" style="padding:0in 0in 0in 0in;width:48.92%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="100%" colspan="3" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">Mitchel Sayare</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="100%" colspan="3" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">President, Chief Executive Officer
  and Chairman of the Board</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="100%" colspan="3" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">ImmunoGen, Inc.</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="100%" colspan="3" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">128 Sidney Street, Cambridge, MA
  02139</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="100%" colspan="3" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">(617)&nbsp;995-2500</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="100%" colspan="3" valign="top" style="padding:0in 0in 0in 0in;width:100.0%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(Name, address, including zip code, and telephone
  number, including area<br>
  code, of agent for service)</font></p>
  </td>
 </tr>
</table>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<div align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">

<hr size="1" width="25%" noshade color="black" align="center">

</font></div>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">CALCULATION OF REGISTRATION FEE</font></b></p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<table border="0" cellspacing="0" cellpadding="0" width="100%" style="border-collapse:collapse;width:100.02%;">
 <tr>
  <td width="25%" valign="bottom" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:25.94%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:8.0pt;font-weight:bold;">Title of<br>
  securities to be registered</font></b></p>
  </td>
  <td width="1%" valign="bottom" style="padding:0in 0in 0in 0in;width:1.88%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="1" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
  <td width="16%" valign="bottom" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:16.2%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:8.0pt;font-weight:bold;">Amount to be<br>
  registered </font></b><b><font size="1" style="font-size:8.0pt;font-weight:bold;">(1)</font></b></p>
  </td>
  <td width="1%" valign="bottom" style="padding:0in 0in 0in 0in;width:1.86%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="1" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
  <td width="16%" colspan="2" valign="bottom" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:16.18%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:8.0pt;font-weight:bold;">Proposed<br>
  maximum<br>
  offering price<br>
  per share </font></b><b><font size="1" style="font-size:8.0pt;font-weight:bold;">(2)</font></b></p>
  </td>
  <td width="1%" valign="bottom" style="padding:0in 0in 0in 0in;width:1.86%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="1" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
  <td width="16%" colspan="2" valign="bottom" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:16.18%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:8.0pt;font-weight:bold;">Proposed<br>
  maximum<br>
  aggregate<br>
  offering price </font></b><b><font size="1" style="font-size:8.0pt;font-weight:bold;">(2)</font></b></p>
  </td>
  <td width="1%" valign="bottom" style="padding:0in 0in 0in 0in;width:1.86%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="1" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
  <td width="16%" colspan="2" valign="bottom" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:16.2%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:8.0pt;font-weight:bold;">Amount of<br>
  registration fee</font></b></p>
  </td>
  <td width="1%" valign="bottom" style="padding:0in 0in 0in 0in;width:1.84%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="1" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="25%" valign="top" style="border:none;padding:0in 0in 0in 0in;width:25.94%;">
  <p style="margin:0in 0in .0001pt 10.0pt;text-indent:-10.0pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Common Stock,
  $.01 par value</font></p>
  </td>
  <td width="1%" valign="bottom" style="padding:0in 0in 0in 0in;width:1.88%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="16%" valign="bottom" style="border:none;padding:0in 0in 0in 0in;width:16.2%;">
  <p align="right" style="margin:0in 0in .0001pt;text-align:right;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">1,200,000</font></p>
  </td>
  <td width="1%" valign="bottom" style="padding:0in 0in 0in 0in;width:1.86%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="1%" valign="bottom" style="border:none;padding:0in 0in 0in 0in;width:1.3%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">$</font></p>
  </td>
  <td width="14%" valign="bottom" style="border:none;border-top:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:14.88%;">
  <p align="right" style="margin:0in 0in .0001pt;text-align:right;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">7.03</font></p>
  </td>
  <td width="1%" valign="bottom" style="padding:0in 0in 0in 0in;width:1.86%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="1%" valign="bottom" style="border:none;padding:0in 0in 0in 0in;width:1.3%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">$</font></p>
  </td>
  <td width="14%" valign="bottom" style="border:none;border-top:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:14.88%;">
  <p align="right" style="margin:0in 0in .0001pt;text-align:right;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">8,436,000</font></p>
  </td>
  <td width="1%" valign="bottom" style="padding:0in 0in 0in 0in;width:1.86%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="1%" valign="bottom" style="border:none;padding:0in 0in 0in 0in;width:1.3%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">$</font></p>
  </td>
  <td width="14%" valign="bottom" style="border:none;border-top:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:14.9%;">
  <p align="right" style="margin:0in 0in .0001pt;text-align:right;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">993.00</font></p>
  </td>
  <td width="1%" valign="bottom" style="padding:0in 0in 0in 0in;width:1.84%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr height="0">
  <td width="194" style="border:none;"></td>
  <td width="14" style="border:none;"></td>
  <td width="121" style="border:none;"></td>
  <td width="14" style="border:none;"></td>
  <td width="10" style="border:none;"></td>
  <td width="111" style="border:none;"></td>
  <td width="14" style="border:none;"></td>
  <td width="10" style="border:none;"></td>
  <td width="111" style="border:none;"></td>
  <td width="14" style="border:none;"></td>
  <td width="10" style="border:none;"></td>
  <td width="111" style="border:none;"></td>
  <td width="14" style="border:none;"></td>
 </tr>
</table>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<div style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">

<hr size="1" width="25%" noshade color="black" align="left">

</font></div>

<p style="font-size:10.0pt;margin:0in 0in .0001pt .25in;text-indent:-.25in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(1)</font><font size="1" style="font-size:3.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font>The
number of shares of common stock, par value<b><font style="font-weight:bold;"> </font></b>$.01 per share
(&#147;Common Stock&#148;), stated above consists of an additional number of shares which
may be sold upon the exercise of options which have been or may hereafter be
granted under the ImmunoGen, Inc. Restated Stock Option Plan (the &#147;Plan&#148;) or
upon the issuance of stock awards which may hereafter be granted under the
Plan. The maximum number of shares which may be sold under the Plan is subject
to adjustment in accordance with certain anti-dilution and other provisions of
the Plan.&#160; Accordingly, pursuant to
Rule&nbsp;416 under the Securities Act of 1933, as amended (the &#147;Securities Act&#148;),
this Registration Statement covers, in addition to the number of shares stated
above, an indeterminate number of shares which may be subject to grant or
otherwise issuable after the operation of any such anti-dilution and other provisions.</p>

<p style="margin:0in 0in .0001pt .25in;text-indent:-.25in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p align="left" style="font-size:10.0pt;letter-spacing:-.1pt;line-height:normal;margin:0in 0in .0001pt .25in;text-align:left;text-indent:-.25in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;letter-spacing:0pt;">(2)</font><font size="1" style="font-size:3.0pt;letter-spacing:0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font><font style="letter-spacing:0pt;">This calculation is made solely for the purpose of
determining the registration fee pursuant to the provisions of Rule&nbsp;457(c)
and (h) under the Securities Act on the basis of the average of the high and
low sale prices per share of the Common Stock on the National Market System of
the National Association of Securities Dealers Automated Quotation System (&#147;Nasdaq&#148;)
as of a date (February 1, 2005) within 5 business days prior to filing this
Registration Statement.</font></p>

<div style="border:none;border-bottom:double windowtext 9.0pt;padding:0in 0in 0in 0in;">

<p style="border:none;margin:0in 0in .0001pt;padding:0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

</div>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<div style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">

<hr size="2" width="100%" noshade color="gray" align="left">

</font></div>

</div>
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<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><u><font size="2" face="Times New Roman" style="font-size:10.0pt;">EXPLANATORY NOTES</font></u></p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">In accordance
with the instructional Note to Part I of Form S-8 as promulgated by the
Securities and Exchange Commission, the information specified by Part I of Form
S-8 has been omitted from this Registration Statement on Form S-8 for offers of
Common Stock pursuant to the Plan. </font></p>

<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">The increase in the number of shares reserved under
the Plan was approved by the Registrant&#146;s stockholders at the 2004 annual
meeting of stockholders pursuant to the </font>Definitive Proxy Statement for Annual Meeting of Stockholders on Schedule
14A, filed on October 6, 2004 (File No. 000-17999). </p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">2</font></p>

<div style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">

<hr size="2" width="100%" noshade color="gray" align="left">

</font></div>

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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">PART II</font></b></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">INFORMATION REQUIRED IN THE
REGISTRATION STATEMENT</font></b></p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt;"><u><font size="2" face="Times New Roman" style="font-size:10.0pt;">Item 3.&#160; Incorporation of Certain Documents by
Reference</font></u>.</p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman"><font style="font-size:10.0pt;">The SEC allows us to &#147;incorporate
by reference&#148; information from other documents that we file with them, which
means that we can disclose important information in this prospectus by
referring to those documents.&#160; The
information incorporated by reference is considered to be part of this
prospectus, and information that we file later with the SEC will automatically
update and supersede the information in this prospectus.&#160; We incorporate by reference the documents
listed below and any future filings made with the SEC under Sections 13(a),
13(c), 14 or 15(d) of the Securities Exchange Act of 1934, </font>excluding any
information furnished to the SEC pursuant to Item 2.02 or Item 7.01 of any
current report on Form 8-K (or any exhibits that are furnished and not filed
pursuant to Item 9.01 of such Form) and any certification furnished to the SEC
as an exhibit to any periodic report on Form 10-K or Form 10-Q</font>.&#160; The
documents we are incorporating by reference as of their respective dates of
filing are:</p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt .75in;text-indent:-.25in;"><font size="3" face="Times New Roman" style="font-size:12.0pt;">&#149;</font><font size="1" style="font-size:3.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font>Current
Report on Form 8-K, filed January 7, 2005, announcing the departure of the CFO
and the appointment of a new principal financial and accounting officer (File No. 000-17999);</p>

<p style="margin:0in 0in .0001pt .75in;text-indent:-.25in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt .75in;text-indent:-.25in;"><font size="3" face="Times New Roman" style="font-size:12.0pt;">&#149;</font><font size="1" style="font-size:3.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font>Current
Report on Form 8-K, filed December 28, 2004, announcing a material definitive
agreement (File No. 000-17999);</p>

<p style="margin:0in 0in .0001pt .75in;text-indent:-.25in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt .75in;text-indent:-.25in;"><font size="3" face="Times New Roman" style="font-size:12.0pt;">&#149;</font><font size="1" style="font-size:3.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font>Quarterly
Report on Form 10-Q for the period ended September 30, 2004, filed on November
9, 2004 (File No. 000-17999);</p>

<p style="margin:0in 0in .0001pt .75in;text-indent:-.25in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt .75in;text-indent:-.25in;"><font size="3" face="Times New Roman" style="font-size:12.0pt;">&#149;</font><font size="1" style="font-size:3.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font>Additional
Soliciting Materials relating to the Definitive Proxy Statement for Annual
Meeting of Stockholders on Schedule 14A, filed on November 4, 2004 (File No.
000-17999);</p>

<p style="margin:0in 0in .0001pt .75in;text-indent:-.25in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt .75in;text-indent:-.25in;"><font size="3" face="Times New Roman" style="font-size:12.0pt;">&#149;</font><font size="1" style="font-size:3.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font>Current
Report on Form 8-K, filed October 27, 2004, announcing the departure of the
registrant&#146;s Vice President, Finance and Treasurer and the appointment of a new
CFO (File No. 000-17999);</p>

<p style="margin:0in 0in .0001pt .75in;text-indent:-.25in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt .75in;text-indent:-.25in;"><font size="3" face="Times New Roman" style="font-size:12.0pt;">&#149;</font><font size="1" style="font-size:3.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font>Current
Report on Form 8-K, filed October 6, 2004, announcing a material definitive
agreement (File No. 000-17999);</p>

<p style="margin:0in 0in .0001pt .75in;text-indent:-.25in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt .75in;text-indent:-.25in;"><font size="3" face="Times New Roman" style="font-size:12.0pt;">&#149;</font><font size="1" style="font-size:3.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font>Definitive
Proxy Statement for Annual Meeting of Stockholders on Schedule 14A, filed on
October 6, 2004 (File No. 000-17999);</p>

<p style="margin:0in 0in .0001pt .75in;text-indent:-.25in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt .75in;text-indent:-.25in;"><font size="3" face="Times New Roman" style="font-size:12.0pt;">&#149;</font><font size="1" style="font-size:3.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font>Our
Annual Report on Form 10-K for the year ended June 30, 2004, filed on August
20, 2004 (File No. 000-17999); and</p>

<p style="margin:0in 0in .0001pt .75in;text-indent:-.25in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt .75in;text-indent:-.25in;"><font size="3" face="Times New Roman" style="font-size:12.0pt;">&#149;</font><font size="1" style="font-size:3.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font>The description of the Company&#146;s
capital stock contained in the Company&#146;s registration statement on Form 8-A
under the Exchange Act (File No. 000-17999), including amendments or reports
filed for the purpose of updating such description.</p>

<p style="margin:0in 0in .0001pt .75in;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">You may request, orally or
in writing, a copy of these filings, which will be provided to you at no cost,
by contacting Mitchel Sayare, President, Chief Executive Officer and Chairman
of the Board, ImmunoGen, Inc., 128 Sidney Street, Cambridge, MA 02139,
(617)&nbsp;995-2500.</font></p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">To
the extent that any statements contained in a document incorporated by
reference are modified or superceded by any statements contained in this
prospectus, such statements shall not be deemed incorporated in this prospectus
except as so modified or superceded.</font></p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">All
documents subsequently filed by us pursuant to Sections 13(a), 13(c), 14 or
15(d) of the Exchange Act and prior to the termination of this offering (</font><font size="2" style="font-size:10.0pt;">other than any
information furnished and not filed with the SEC on any current report on Form
8-K or any exhibits furnished pursuant to Item 9.01 of such Form) and other
than any certification furnished to the SEC as an exhibit to any periodic report
on Form 10-K or Form 10-Q) </font><font size="2" style="font-size:10.0pt;">are incorporated by reference and become a
part of this prospectus from the date such documents are filed. Any statement
contained in this</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">3</font></p>

<div style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">

<hr size="2" width="100%" noshade color="gray" align="left">

</font></div>

</div>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">prospectus
or in a document incorporated by reference is modified or superceded for
purposes of this prospectus to the extent that a statement contained in any
subsequent filed document modifies or supercedes such statement.</font></p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt;"><u><font size="2" face="Times New Roman" style="font-size:10.0pt;">Item 4.&#160; Description of Securities</font></u>.</p>

<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p align="left" style="margin:0in 0in .0001pt;text-align:left;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Not applicable.</font></p>

<p align="left" style="margin:0in 0in .0001pt;text-align:left;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt;"><u><font size="2" face="Times New Roman" style="font-size:10.0pt;">Item 5.&#160; Interests of Named Experts and Counsel</font></u>.</p>

<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p align="left" style="margin:0in 0in .0001pt;text-align:left;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Members of Mintz, Levin,
Cohn, Ferris, Glovsky and Popeo, P.C. beneficially own no shares of Common
Stock of the Company.</font></p>

<p align="left" style="margin:0in 0in .0001pt;text-align:left;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt;"><u><font size="2" face="Times New Roman" style="font-size:10.0pt;">Item 6.&#160; Indemnification of Directors and Officers</font></u>.</p>

<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Article&nbsp;6(d) of
ImmunoGen,&nbsp;Inc.&#146;s Restated Articles of Organization provides as follows:</font></p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="margin:0in 0in .0001pt;text-indent:.25in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&#147;(d)
The liability of the Directors of the Corporation shall be limited to the
fullest extent permitted by Section&nbsp;13(b)(1<sup>1</sup>/</font><font size="2" style="font-size:10.0pt;">2</font><font size="2" style="font-size:10.0pt;">) of the Massachusetts Business
Corporation Law.&#148;</font></p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="margin:0in 0in .0001pt;text-indent:.25in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Section&nbsp;6.6
of the ImmunoGen,&nbsp;Inc.&#146;s By-Laws provides as follows:</font></p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="margin:0in 0in .0001pt;text-indent:.25in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&#147;Section&nbsp;6.6
Indemnification of Officers, Directors, and Members of the Scientific Advisory
Board. The corporation shall indemnify and hold harmless each person, now or
hereafter an officer or Director of the corporation, or a member of the
Scientific Advisory Board, from and against any and all claims and liabilities
to which he may be or become subject by reason of his being or having been an
officer, Director or member of the Scientific Advisory Board of the corporation
or by reason of his alleged acts or omissions as an officer, Director or member
of the Scientific Advisory Board of the corporation, and shall indemnify and
reimburse each such officer, Director and member of the Scientific Advisory
Board against and for any and all legal and other expenses reasonably incurred
by him in connection with any such claims and liabilities, actual or
threatened, whether or not at or prior to the time which so indemnified, held
harmless and reimbursed he has ceased to be an officer, Director or member of
the Scientific Advisory Board of the corporation, except with respect to any
matter as to which such officer, Director or member of the Scientific Advisory
Board of the corporation shall have been adjudicated in any proceeding not to
have acted in good faith in the reasonable belief that his action was in the
best interest of the corporation; provided, however, that prior to such final
adjudication the corporation may compromise and settle any such claims and
liabilities and pay such expenses, if such settlement or payment or both
appears, in the judgment of a majority of those members of the Board of
Directors who are not involved in such matters, to be for the best interest of
the corporation as evidenced by a resolution to that effect adopted after
receipt by the corporation of a written opinion of counsel for the corporation,
that, based on the facts available to such counsel, such officer, Director or
member of the Scientific Advisory Board of the corporation has not been guilty
of acting in a manner that would prohibit indemnification.</font></p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="margin:0in 0in .0001pt;text-indent:.25in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Such
indemnification may include payment by the corporation of expenses incurred in
defending a civil or criminal action or proceeding in advance of the final
disposition of such action or proceeding, upon receipt of an undertaking by the
person indemnified to repay such payment if he shall be adjudicated not to be
entitled to indemnification under this section.</font></p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="margin:0in 0in .0001pt;text-indent:.25in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">The
corporation shall similarly indemnify and hold harmless persons who serve at
its express written request as directors or officers of another organization in
which the corporation owns shares or of which it is a creditor.</font></p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="margin:0in 0in .0001pt;text-indent:.25in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">The
right of indemnification herein provided shall be in addition to and not
exclusive of any other rights to which any officer, Director or member of the
Scientific Advisory Board of the corporation, or any such persons who serve at
its request as aforesaid, may otherwise be lawfully entitled. As used in this
Section, the terms &#147;officer,&#148;</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">4</font></p>

<div style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">

<hr size="2" width="100%" noshade color="gray" align="left">

</font></div>

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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&#147;Director,&#148; and &#147;member
of the Scientific Advisory Board&#148; include their respective heirs, executors,
and administrators.&#148;</font></p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt;"><u><font size="2" face="Times New Roman" style="font-size:10.0pt;">Item 7.&#160; Exemption from Registration Claimed</font></u>.</p>

<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Not applicable.</font></p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt;"><u><font size="2" face="Times New Roman" style="font-size:10.0pt;">Item 8.&#160; Exhibits</font></u>.</p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<table border="0" cellspacing="0" cellpadding="0" width="92%" style="border-collapse:collapse;margin-left:.5in;width:92.0%;">
 <tr>
  <td width="5%" valign="top" style="padding:0in 0in 0in 0in;width:5.7%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(3.1)</font></p>
  </td>
  <td width="3%" valign="bottom" style="padding:0in 0in 0in 0in;width:3.08%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="91%" valign="top" style="padding:0in 0in 0in 0in;width:91.22%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Restated Articles of
  Organization of the Registrant (previously filed as Exhibit&nbsp;3.1 to the
  Registrant&#146;s Quarterly Report on Form&nbsp;10-Q for the quarter ended
  September&nbsp;30, 1996, File No.&nbsp;0-17999, and incorporated herein by
  reference).</font></p>
  </td>
 </tr>
 <tr>
  <td width="5%" valign="top" style="padding:0in 0in 0in 0in;width:5.7%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="3%" valign="bottom" style="padding:0in 0in 0in 0in;width:3.08%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="91%" valign="top" style="padding:0in 0in 0in 0in;width:91.22%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="5%" valign="top" style="padding:0in 0in 0in 0in;width:5.7%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(3.2)</font></p>
  </td>
  <td width="3%" valign="bottom" style="padding:0in 0in 0in 0in;width:3.08%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="91%" valign="top" style="padding:0in 0in 0in 0in;width:91.22%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Amendment to Articles
  of Organization of the Registrant (previously filed as Exhibit&nbsp;3.1 to
  the Registrant&#146;s Quarterly Report on Form&nbsp;10-Q for the quarter ended
  December&nbsp;31, 2001, File No.&nbsp;0-17999, and incorporated herein by
  reference).</font></p>
  </td>
 </tr>
 <tr>
  <td width="5%" valign="top" style="padding:0in 0in 0in 0in;width:5.7%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="3%" valign="bottom" style="padding:0in 0in 0in 0in;width:3.08%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="91%" valign="top" style="padding:0in 0in 0in 0in;width:91.22%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="5%" valign="top" style="padding:0in 0in 0in 0in;width:5.7%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(3.3)</font></p>
  </td>
  <td width="3%" valign="bottom" style="padding:0in 0in 0in 0in;width:3.08%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="91%" valign="top" style="padding:0in 0in 0in 0in;width:91.22%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">By-laws of the
  Registrant, as amended (previously filed as Exhibit&nbsp;3.2 to the
  Registrant&#146;s Annual Report on Form&nbsp;10-K for the fiscal year ended
  June&nbsp;30, 1990, File No.&nbsp;0-17999, and incorporated herein by
  reference).</font></p>
  </td>
 </tr>
 <tr>
  <td width="5%" valign="top" style="padding:0in 0in 0in 0in;width:5.7%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="3%" valign="bottom" style="padding:0in 0in 0in 0in;width:3.08%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="91%" valign="top" style="padding:0in 0in 0in 0in;width:91.22%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="5%" valign="top" style="padding:0in 0in 0in 0in;width:5.7%;">
  <p style="margin:0in 0in .0001pt;text-indent:0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(4.1)</font></p>
  </td>
  <td width="3%" valign="bottom" style="padding:0in 0in 0in 0in;width:3.08%;">
  <p style="margin:0in 0in .0001pt;text-indent:0in;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="91%" valign="top" style="padding:0in 0in 0in 0in;width:91.22%;">
  <p style="margin:0in 0in .0001pt;text-indent:0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Form of Common Stock Certificate (previously filed
  as Exhibit&nbsp;4.2 to the Registrant&#146;s Registration Statement on
  Form&nbsp;S-1, File No.&nbsp;333-31219, and incorporated herein by
  reference).</font></p>
  </td>
 </tr>
 <tr>
  <td width="5%" valign="top" style="padding:0in 0in 0in 0in;width:5.7%;">
  <p style="margin:0in 0in .0001pt;text-indent:0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="3%" valign="bottom" style="padding:0in 0in 0in 0in;width:3.08%;">
  <p style="margin:0in 0in .0001pt;text-indent:0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="91%" valign="top" style="padding:0in 0in 0in 0in;width:91.22%;">
  <p style="margin:0in 0in .0001pt;text-indent:0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="5%" valign="top" style="padding:0in 0in 0in 0in;width:5.7%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(5)</font></p>
  </td>
  <td width="3%" valign="bottom" style="padding:0in 0in 0in 0in;width:3.08%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="91%" valign="top" style="padding:0in 0in 0in 0in;width:91.22%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Opinion of Mintz,
  Levin, Cohn, Ferris, Glovsky and Popeo, P.C. as to the legality of shares
  being registered.</font></p>
  </td>
 </tr>
 <tr>
  <td width="5%" valign="top" style="padding:0in 0in 0in 0in;width:5.7%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="3%" valign="bottom" style="padding:0in 0in 0in 0in;width:3.08%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="91%" valign="top" style="padding:0in 0in 0in 0in;width:91.22%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="5%" valign="top" style="padding:0in 0in 0in 0in;width:5.7%;">
  <p style="margin:0in 0in .0001pt;text-indent:0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(23.1)</font></p>
  </td>
  <td width="3%" valign="bottom" style="padding:0in 0in 0in 0in;width:3.08%;">
  <p style="margin:0in 0in .0001pt;text-indent:0in;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="91%" valign="top" style="padding:0in 0in 0in 0in;width:91.22%;">
  <p style="margin:0in 0in .0001pt;text-indent:0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Consent of Mintz, Levin, Cohn, Ferris, Glovsky and
  Popeo, P.C. (included in opinion of counsel filed as Exhibit 5).</font></p>
  </td>
 </tr>
 <tr>
  <td width="5%" valign="top" style="padding:0in 0in 0in 0in;width:5.7%;">
  <p style="margin:0in 0in .0001pt;text-indent:0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="3%" valign="bottom" style="padding:0in 0in 0in 0in;width:3.08%;">
  <p style="margin:0in 0in .0001pt;text-indent:0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="91%" valign="top" style="padding:0in 0in 0in 0in;width:91.22%;">
  <p style="margin:0in 0in .0001pt;text-indent:0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="5%" valign="top" style="padding:0in 0in 0in 0in;width:5.7%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(23.2)</font></p>
  </td>
  <td width="3%" valign="bottom" style="padding:0in 0in 0in 0in;width:3.08%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="91%" valign="top" style="padding:0in 0in 0in 0in;width:91.22%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Consent of Ernst &amp;
  Young LLP.</font></p>
  </td>
 </tr>
 <tr>
  <td width="5%" valign="top" style="padding:0in 0in 0in 0in;width:5.7%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="3%" valign="bottom" style="padding:0in 0in 0in 0in;width:3.08%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="91%" valign="top" style="padding:0in 0in 0in 0in;width:91.22%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="5%" valign="top" style="padding:0in 0in 0in 0in;width:5.7%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(24)</font></p>
  </td>
  <td width="3%" valign="bottom" style="padding:0in 0in 0in 0in;width:3.08%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="91%" valign="top" style="padding:0in 0in 0in 0in;width:91.22%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Power of Attorney
  (included on the signature page of the Registration Statement).</font></p>
  </td>
 </tr>
 <tr>
  <td width="5%" valign="top" style="padding:0in 0in 0in 0in;width:5.7%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="3%" valign="bottom" style="padding:0in 0in 0in 0in;width:3.08%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="91%" valign="top" style="padding:0in 0in 0in 0in;width:91.22%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="5%" valign="top" style="padding:0in 0in 0in 0in;width:5.7%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(99.1)</font></p>
  </td>
  <td width="3%" valign="bottom" style="padding:0in 0in 0in 0in;width:3.08%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="91%" valign="top" style="padding:0in 0in 0in 0in;width:91.22%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">ImmunoGen, Inc.
  Restated Stock Option Plan as amended on February 2, 2005.</font></p>
  </td>
 </tr>
</table>

<p style="margin:0in 0in .0001pt 70.8pt;text-indent:-34.8pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt;"><u><font size="2" face="Times New Roman" style="font-size:10.0pt;">Item 9.&#160; Undertakings</font></u>.</p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt .5in;text-indent:-.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(a)</font><font size="1" style="font-size:3.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font>The
undersigned Registrant hereby undertakes:</p>

<p style="margin:0in 0in .0001pt .5in;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt .5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(1)</font><font size="1" style="font-size:3.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font>To
file, during any period in which offers or sales are being made, a
post-effective amendment to this Registration Statement:</p>

<p style="margin:0in 0in .0001pt .5in;text-indent:1.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt 1.0in;text-indent:.25in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(i)</font><font size="1" style="font-size:3.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font>To
include any prospectus required by Section 10(a)(3) of the Securities Act of
1933;</p>

<p style="margin:0in 0in .0001pt 1.0in;text-indent:1.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt 1.0in;text-indent:.25in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(ii)</font><font size="1" style="font-size:3.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font>To
reflect in the prospectus any facts or events arising after the effective date
of the Registration Statement (or the most recent post-effective amendment
thereof) which, individually or in the aggregate, represents a fundamental
change in the information set forth in the Registration Statement.&#160; Notwithstanding the foregoing, any increase or
decrease in volume of securities offered (if</p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">5</font></p>

<div style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">

<hr size="2" width="100%" noshade color="gray" align="left">

</font></div>

</div>
<!-- SEQ.=1,FOLIO='5',FILE='C:\JMS\rdesika\05-2782-1\task292433\2782-1-ba.htm',USER='hkrishnamurthy',CD='Feb  4 21:43 2005' -->


<br clear="all" style="page-break-before:always;">


<div style="font-family:Times New Roman;">

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="margin:0in 0in .0001pt 1.0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">the
total dollar value of securities offered would not exceed that which was
registered) and any deviation from the low or high end of the estimated maximum
offering range may be reflected in the form of prospectus filed with the
Commission pursuant to Rule 424(b) (Section 230.424(b) of this chapter) if, in
the aggregate, the changes in volume and price represent no more than a 20%
change in the maximum aggregate offering price set forth in the &#147;Calculation of
Registration Fee&#148; table in the effective Registration Statement.</font></p>

<p style="margin:0in 0in .0001pt 1.0in;text-indent:1.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt 1.0in;text-indent:.25in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(iii)</font><font size="1" style="font-size:3.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font>To include any material
information with respect to the plan of distribution not previously disclosed
in the Registration Statement or any material change to such information in the
Registration Statement;</p>

<p style="margin:0in 0in .0001pt 1.0in;text-indent:1.0in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt .5in;text-indent:.5in;"><i><font size="2" face="Times New Roman" style="font-size:10.0pt;font-style:italic;">Provided, however</font></i>, that
paragraphs (a)(1)(i) and (a)(1)(ii) do not apply if the Registration Statement
is on Form S-3, Form S-8 or Form F-3, and the information required to be
included in a post-effective amendment by those paragraphs is contained in
periodic reports filed with or furnished to the Commission by the Registrant
pursuant to Section 13 or Section 15(d) of the Securities Exchange Act of 1934
that are incorporated by reference in this Registration Statement.</p>

<p style="margin:0in 0in .0001pt .5in;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt .5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(2)</font><font size="1" style="font-size:3.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font>That,
for the purpose of determining any liability under the Securities Act of 1933,
each such post-effective amendment shall be deemed to be a new registration
statement relating to the securities offered therein, and the offering of such
securities at that time shall be deemed to be the initial bona fide offering
thereof.</p>

<p style="margin:0in 0in .0001pt .5in;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt .5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(3)</font><font size="1" style="font-size:3.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font>To
remove from registration by means of a post-effective amendment any of the
securities being registered which remain unsold at the termination of the
offering.</p>

<p style="margin:0in 0in .0001pt .5in;text-indent:-.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt .5in;text-indent:-.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(b)</font><font size="1" style="font-size:3.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font>The
undersigned Registrant hereby undertakes that, for purposes of determining any
liability under the Securities Act of 1933, each filing of the Registrant&#146;s
annual report pursuant to Section 13(a) or Section 15(d) of the Securities
Exchange Act of 1934 that is incorporated by reference in this Registration
Statement shall be deemed to be a new registration statement relating to the
securities offered therein, and the offering of such securities at that time
shall be deemed to be the initial bona fide offering thereof.</p>

<p style="margin:0in 0in .0001pt .5in;text-indent:-.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="font-size:10.0pt;margin:0in 0in .0001pt .5in;text-indent:-.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(c)</font><font size="1" style="font-size:3.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font>Insofar
as indemnification for liabilities arising under the Securities Act of 1933 may
be permitted to directors, officers and controlling persons of the Registrant
pursuant to the foregoing provisions, or otherwise, the Registrant has been
advised that in the opinion of the Securities and Exchange Commission such
indemnification is against public policy as expressed in the Act and is,
therefore, unenforceable.&#160; In the event
that a claim for indemnification against such liabilities (other than the payment
by the Registrant of expenses incurred or paid by a director, officer or
controlling person of the Registrant in the successful defense of any action,
suit or proceeding) is asserted by such director, officer or controlling person
in connection with the securities being registered, the Registrant will, unless
in the opinion of its counsel the matter has been settled by controlling
precedent, submit to a court of appropriate jurisdiction the question whether
such indemnification by it is against public policy as expressed in the Act and
will be governed by the final adjudication of such issue.</p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">6</font></p>

<div style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">

<hr size="2" width="100%" noshade color="gray" align="left">

</font></div>

</div>
<!-- SEQ.=1,FOLIO='6',FILE='C:\JMS\rdesika\05-2782-1\task292433\2782-1-ba.htm',USER='hkrishnamurthy',CD='Feb  4 21:43 2005' -->


<br clear="all" style="page-break-before:always;">


<div>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">SIGNATURES</font></b></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Pursuant to the
requirements of the Securities Act of 1933, the Registrant certifies that it
has reasonable grounds to believe that it meets all of the requirements for
filing on Form S-8 and has duly caused this Registration Statement to be signed
on its behalf by the undersigned, thereunto duly authorized, in Cambridge,
Massachusetts on February 4, 2005.</font></p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<table border="0" cellspacing="0" cellpadding="0" width="100%" style="border-collapse:collapse;width:100.0%;">
 <tr>
  <td width="57%" valign="top" style="padding:0in 0in 0in 0in;width:57.4%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="42%" colspan="3" valign="top" style="padding:0in 0in 0in 0in;width:42.6%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">IMMUNOGEN, INC.</font></p>
  </td>
 </tr>
 <tr>
  <td width="57%" valign="top" style="padding:0in 0in 0in 0in;width:57.4%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="42%" colspan="3" valign="top" style="padding:0in 0in 0in 0in;width:42.6%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="57%" valign="top" style="padding:0in 0in 0in 0in;width:57.4%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="42%" colspan="3" valign="top" style="padding:0in 0in 0in 0in;width:42.6%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="57%" valign="top" style="padding:0in 0in 0in 0in;width:57.4%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="4%" valign="top" style="padding:0in 0in 0in 0in;width:4.26%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">By:</font></p>
  </td>
  <td width="29%" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:29.76%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">/s/ Mitchel Sayare</font></p>
  </td>
  <td width="8%" valign="top" style="padding:0in 0in 0in 0in;width:8.58%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="57%" valign="top" style="padding:0in 0in 0in 0in;width:57.4%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="42%" colspan="3" valign="top" style="padding:0in 0in 0in 0in;width:42.6%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Chairman of the Board
  of Directors, President and Chief<br>
  Executive Officer (principal executive officer)</font></p>
  </td>
 </tr>
</table>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Each person whose
signature appears below constitutes and appoints Mitchel Sayare, and each of
them, his or her true and lawful attorneys-in-fact and agents, with full power
of substitution and resubstitution in each of them, for him or her and in his
or her name, place and stead, and in any and all capacities, to sign any and
all amendments (including post-effective amendments) to this Registration
Statement on Form S-8 of ImmunoGen, Inc., and to file the same, with all
exhibits thereto and other documents in connection therewith, with the
Securities and Exchange Commission, granting unto said attorneys-in-fact and
agents, and each of them, full power and authority to do and perform each and
every act and thing requisite or necessary to be done in or about the premises,
as full to all intents and purposes as he or she might or could do in person,
hereby ratifying and confirming all that said attorneys-in-fact and agents or
any of them or their or his or her substitute or substitutes may lawfully do or
cause to be done by virtue hereof.</font></p>

<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Pursuant to the requirements of the Securities Act of
1933, this Registration Statement has been signed by the following persons in
the capacities and on the dates indicated.</font></p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<table border="0" cellspacing="0" cellpadding="0" width="100%" style="border-collapse:collapse;width:100.0%;">
 <tr>
  <td width="35%" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:35.18%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:8.0pt;font-weight:bold;">SIGNATURE</font></b></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="1" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="43%" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:43.48%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:8.0pt;font-weight:bold;">TITLE</font></b></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
  <td width="15%" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:15.68%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:8.0pt;font-weight:bold;">DATE</font></b></p>
  </td>
  <td width="1%" valign="top" style="padding:0in 0in 0in 0in;width:1.38%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="35%" valign="bottom" style="padding:0in 0in 0in 0in;width:35.18%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
  <td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.48%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
  <td width="15%" style="padding:0in 0in 0in 0in;width:15.68%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="1%" valign="top" style="padding:0in 0in 0in 0in;width:1.38%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="35%" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:35.18%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">/s/ MITCHEL
  SAYARE</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
  <td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.48%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Chairman of the Board
  of</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
  <td width="15%" valign="top" style="padding:0in 0in 0in 0in;width:15.68%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="1%" valign="top" style="padding:0in 0in 0in 0in;width:1.38%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="35%" valign="top" style="border:none;padding:0in 0in 0in 0in;width:35.18%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Mitchel Sayare</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
  <td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.48%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Directors, President
  and Chief<br>
  Executive Officer (principal<br>
  executive officer)</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
  <td width="15%" valign="top" style="padding:0in 0in 0in 0in;width:15.68%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">February 4, 2005</font></p>
  </td>
  <td width="1%" valign="top" style="padding:0in 0in 0in 0in;width:1.38%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="35%" valign="top" style="padding:0in 0in 0in 0in;width:35.18%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
  <td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.48%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
  <td width="15%" valign="top" style="padding:0in 0in 0in 0in;width:15.68%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="1%" valign="top" style="padding:0in 0in 0in 0in;width:1.38%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="35%" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:35.18%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">/s/ WALTER A.
  BL&#196;TTLER</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
  <td width="43%" rowspan="2" valign="top" style="padding:0in 0in 0in 0in;width:43.48%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Executive Vice
  President, Science<br>
  and Technology and Director</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
  <td width="15%" valign="top" style="padding:0in 0in 0in 0in;width:15.68%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">February 4, 2005</font></p>
  </td>
  <td width="1%" valign="top" style="padding:0in 0in 0in 0in;width:1.38%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="2" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="35%" valign="top" style="border:none;padding:0in 0in 0in 0in;width:35.18%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Walter A.
  Bl&#228;ttler</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="15%" valign="top" style="padding:0in 0in 0in 0in;width:15.68%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="1%" valign="top" style="padding:0in 0in 0in 0in;width:1.38%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="35%" valign="top" style="padding:0in 0in 0in 0in;width:35.18%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.48%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="15%" valign="top" style="padding:0in 0in 0in 0in;width:15.68%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="1%" valign="top" style="padding:0in 0in 0in 0in;width:1.38%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="35%" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:35.18%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">/s/ KARLEEN M.
  OBERTON</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="43%" rowspan="2" valign="top" style="padding:0in 0in 0in 0in;width:43.48%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Senior Corporate
  Controller<br>
  (principal financial and accounting<br>
  officer)</font></p>
  </td>
  <td width="2%" rowspan="2" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="15%" rowspan="2" valign="top" style="padding:0in 0in 0in 0in;width:15.68%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">February 4, 2005</font></p>
  </td>
  <td width="1%" rowspan="2" valign="top" style="padding:0in 0in 0in 0in;width:1.38%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="35%" valign="top" style="border:none;padding:0in 0in 0in 0in;width:35.18%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Karleen M.
  Oberton</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="35%" valign="top" style="padding:0in 0in 0in 0in;width:35.18%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.48%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="15%" valign="top" style="padding:0in 0in 0in 0in;width:15.68%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="1%" valign="top" style="padding:0in 0in 0in 0in;width:1.38%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="35%" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:35.18%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">/s/ DAVID W.
  CARTER</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.48%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Director</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="15%" valign="top" style="padding:0in 0in 0in 0in;width:15.68%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">February 4, 2005</font></p>
  </td>
  <td width="1%" valign="top" style="padding:0in 0in 0in 0in;width:1.38%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="35%" valign="top" style="border:none;padding:0in 0in 0in 0in;width:35.18%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">David W. Carter</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.48%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="15%" valign="top" style="padding:0in 0in 0in 0in;width:15.68%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="1%" valign="top" style="padding:0in 0in 0in 0in;width:1.38%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
 </tr>
</table>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">7</font></p>

<div style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">

<hr size="2" width="100%" noshade color="gray" align="left">

</font></div>

</div>
<!-- SEQ.=1,FOLIO='7',FILE='C:\JMS\rdesika\05-2782-1\task292433\2782-1-ba.htm',USER='hkrishnamurthy',CD='Feb  4 21:43 2005' -->


<br clear="all" style="page-break-before:always;">


<div>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<table border="0" cellspacing="0" cellpadding="0" width="100%" style="border-collapse:collapse;width:100.0%;">
 <tr>
  <td width="35%" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:35.18%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">/s/ STUART F.
  FEINER</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.48%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Director</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="15%" valign="top" style="padding:0in 0in 0in 0in;width:15.68%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">February 4, 2005</font></p>
  </td>
  <td width="1%" valign="top" style="padding:0in 0in 0in 0in;width:1.38%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="35%" valign="top" style="border:none;padding:0in 0in 0in 0in;width:35.18%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Stuart F. Feiner</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.48%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="15%" valign="top" style="padding:0in 0in 0in 0in;width:15.68%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="1%" valign="top" style="padding:0in 0in 0in 0in;width:1.38%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="35%" valign="top" style="padding:0in 0in 0in 0in;width:35.18%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.48%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="15%" valign="top" style="padding:0in 0in 0in 0in;width:15.68%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="1%" valign="top" style="padding:0in 0in 0in 0in;width:1.38%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="35%" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:35.18%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">/s/ MARK
  SKALETSKY</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.48%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Director</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="15%" valign="top" style="padding:0in 0in 0in 0in;width:15.68%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">February 4, 2005</font></p>
  </td>
  <td width="1%" valign="top" style="padding:0in 0in 0in 0in;width:1.38%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="35%" valign="top" style="border:none;padding:0in 0in 0in 0in;width:35.18%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Mark Skaletsky</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.48%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="15%" valign="top" style="padding:0in 0in 0in 0in;width:15.68%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="1%" valign="top" style="padding:0in 0in 0in 0in;width:1.38%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="35%" valign="top" style="padding:0in 0in 0in 0in;width:35.18%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.48%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="15%" valign="top" style="padding:0in 0in 0in 0in;width:15.68%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="1%" valign="top" style="padding:0in 0in 0in 0in;width:1.38%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="35%" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:35.18%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">/s/ JOSEPH J.
  VILLAFRANCA</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.48%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Director</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="15%" valign="top" style="padding:0in 0in 0in 0in;width:15.68%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">February 4, 2005</font></p>
  </td>
  <td width="1%" valign="top" style="padding:0in 0in 0in 0in;width:1.38%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="35%" valign="top" style="border:none;padding:0in 0in 0in 0in;width:35.18%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Joseph J.
  Villafranca</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="43%" valign="top" style="padding:0in 0in 0in 0in;width:43.48%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="2%" valign="top" style="padding:0in 0in 0in 0in;width:2.14%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="15%" valign="top" style="padding:0in 0in 0in 0in;width:15.68%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="1%" valign="top" style="padding:0in 0in 0in 0in;width:1.38%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
 </tr>
</table>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">8</font></p>

<div style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">

<hr size="2" width="100%" noshade color="gray" align="left">

</font></div>

</div>
<!-- SEQ.=1,FOLIO='8',FILE='C:\JMS\rdesika\05-2782-1\task292433\2782-1-ba.htm',USER='hkrishnamurthy',CD='Feb  4 21:43 2005' -->


<br clear="all" style="page-break-before:always;">


<div>

<p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">IMMUNOGEN, INC.</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">INDEX TO EXHIBITS
FILED WITH</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">FORM S-8
REGISTRATION STATEMENT</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<table border="0" cellspacing="0" cellpadding="0" width="100%" style="border-collapse:collapse;width:100.0%;">
 <tr>
  <td width="7%" valign="top" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:7.08%;">
  <p style="margin:0in 0in .0001pt;"><b><font size="1" face="Times New Roman" style="font-size:8.0pt;font-weight:bold;">Exhibit <br>
  Number</font></b></p>
  </td>
  <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.76%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:1.0pt;font-weight:bold;">&nbsp;</font></b></p>
  </td>
  <td width="90%" valign="bottom" style="border:none;border-bottom:solid windowtext 1.0pt;padding:0in 0in 0in 0in;width:90.16%;">
  <p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="1" face="Times New Roman" style="font-size:8.0pt;font-weight:bold;">Description</font></b></p>
  </td>
 </tr>
 <tr>
  <td width="7%" valign="top" style="border:none;padding:0in 0in 0in 0in;width:7.08%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.76%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="90%" valign="top" style="border:none;padding:0in 0in 0in 0in;width:90.16%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="7%" valign="top" style="padding:0in 0in 0in 0in;width:7.08%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">5</font></p>
  </td>
  <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.76%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="90%" valign="top" style="padding:0in 0in 0in 0in;width:90.16%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Opinion of Mintz,
  Levin, Cohn, Ferris, Glovsky and Popeo, P.C. as to the legality of shares
  being registered.</font></p>
  </td>
 </tr>
 <tr>
  <td width="7%" valign="top" style="padding:0in 0in 0in 0in;width:7.08%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.76%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="90%" valign="top" style="padding:0in 0in 0in 0in;width:90.16%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="7%" valign="top" style="padding:0in 0in 0in 0in;width:7.08%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">23.1</font></p>
  </td>
  <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.76%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="90%" valign="top" style="padding:0in 0in 0in 0in;width:90.16%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Consent of Mintz, Levin,
  Cohn, Ferris, Glovsky and Popeo, P.C (included in opinion of counsel filed as
  Exhibit 5).</font></p>
  </td>
 </tr>
 <tr>
  <td width="7%" valign="top" style="padding:0in 0in 0in 0in;width:7.08%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.76%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="90%" valign="top" style="padding:0in 0in 0in 0in;width:90.16%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="7%" valign="top" style="padding:0in 0in 0in 0in;width:7.08%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">23.2</font></p>
  </td>
  <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.76%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="90%" valign="top" style="padding:0in 0in 0in 0in;width:90.16%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Consent of Ernst &amp;
  Young LLP.</font></p>
  </td>
 </tr>
 <tr>
  <td width="7%" valign="top" style="padding:0in 0in 0in 0in;width:7.08%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.76%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="90%" valign="top" style="padding:0in 0in 0in 0in;width:90.16%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="7%" valign="top" style="padding:0in 0in 0in 0in;width:7.08%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">24</font></p>
  </td>
  <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.76%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="90%" valign="top" style="padding:0in 0in 0in 0in;width:90.16%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Power of Attorney
  (included on the signature page of the Registration Statement).</font></p>
  </td>
 </tr>
 <tr>
  <td width="7%" valign="top" style="padding:0in 0in 0in 0in;width:7.08%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.76%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
  <td width="90%" valign="top" style="padding:0in 0in 0in 0in;width:90.16%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>
  </td>
 </tr>
 <tr>
  <td width="7%" valign="top" style="padding:0in 0in 0in 0in;width:7.08%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">99.1</font></p>
  </td>
  <td width="2%" valign="bottom" style="padding:0in 0in 0in 0in;width:2.76%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>
  </td>
  <td width="90%" valign="top" style="padding:0in 0in 0in 0in;width:90.16%;">
  <p style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">ImmunoGen, Inc. Restated
  Stock Option Plan as amended on February 2, 2005.</font></p>
  </td>
 </tr>
</table>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">&nbsp;</font></p>

<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">9</font></p>

<div style="margin:0in 0in .0001pt;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">

<hr size="2" width="100%" noshade color="gray" align="left">

</font></div>

</div>
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{"company-data": {"conformed-name": "IMMUNOGEN INC", "cik": "0000855654", "assigned-sic": "2834", "irs-number": "042726691", "state-of-incorporation": "MA", "fiscal-year-end": "0630"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-122553", "film-number": "05576467"}, "business-address": {"street1": "128 SIDNEY ST", "city": "CAMBRIDGE", "state": "MA", "zip": "02139", "phone": "6179952506"}, "mail-address": {"street1": "128 SIDNEY ST", "city": "CAMBRIDGE", "state": "MA", "zip": "02139"}}
As filed with the
Securities and Exchange Commission on February 4, 2005
REGISTRATION NO. 333-
UNITED
STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549
FORM S-8
REGISTRATION
STATEMENT
under
the
SECURITIES
ACT OF 1933
IMMUNOGEN,
INC.
(Exact name of Registrant
as specified in its charter)
Massachusetts
04-2726691
(State or other
  jurisdiction
(I.R.S. Employer
of incorporation or
  organization)
Identification No.)
128 Sidney Street, Cambridge, MA
  02139
(617) 995-2500
(Address of Principal Executive Offices)
RESTATED STOCK OPTION PLAN
(Full Title of the Plan)
Mitchel Sayare
President, Chief Executive Officer
  and Chairman of the Board
ImmunoGen, Inc.
128 Sidney Street, Cambridge, MA
  02139
(617) 995-2500
(Name, address, including zip code, and telephone
  number, including area
code, of agent for service)
CALCULATION OF REGISTRATION FEE
Title of
securities to be registered
Amount to be
registered
(1)
Proposed
maximum
offering price
per share
(2)
Proposed
maximum
aggregate
offering price
(2)
Amount of
registration fee
Common Stock,
  $.01 par value
1,200,000
$
7.03
$
8,436,000
$
993.00
(1)
The
number of shares of common stock, par value
$.01 per share
("Common Stock"), stated above consists of an additional number of shares which
may be sold upon the exercise of options which have been or may hereafter be
granted under the ImmunoGen, Inc. Restated Stock Option Plan (the "Plan") or
upon the issuance of stock awards which may hereafter be granted under the
Plan. The maximum number of shares which may be sold under the Plan is subject
to adjustment in accordance with certain anti-dilution and other provisions of
the Plan.  Accordingly, pursuant to
Rule 416 under the Securities Act of 1933, as amended (the "Securities Act"),
this Registration Statement covers, in addition to the number of shares stated
above, an indeterminate number of shares which may be subject to grant or
otherwise issuable after the operation of any such anti-dilution and other provisions.
(2)
This calculation is made solely for the purpose of
determining the registration fee pursuant to the provisions of Rule 457(c)
and (h) under the Securities Act on the basis of the average of the high and
low sale prices per share of the Common Stock on the National Market System of
the National Association of Securities Dealers Automated Quotation System ("Nasdaq")
as of a date (February 1, 2005) within 5 business days prior to filing this
Registration Statement.
EXPLANATORY NOTES
In accordance
with the instructional Note to Part I of Form S-8 as promulgated by the
Securities and Exchange Commission, the information specified by Part I of Form
S-8 has been omitted from this Registration Statement on Form S-8 for offers of
Common Stock pursuant to the Plan.
The increase in the number of shares reserved under
the Plan was approved by the Registrant's stockholders at the 2004 annual
meeting of stockholders pursuant to the
Definitive Proxy Statement for Annual Meeting of Stockholders on Schedule
14A, filed on October 6, 2004 (File No. 000-17999).
2
PART II
INFORMATION REQUIRED IN THE
REGISTRATION STATEMENT
Item 3.  Incorporation of Certain Documents by
Reference
.
The SEC allows us to "incorporate
by reference" information from other documents that we file with them, which
means that we can disclose important information in this prospectus by
referring to those documents.  The
information incorporated by reference is considered to be part of this
prospectus, and information that we file later with the SEC will automatically
update and supersede the information in this prospectus.  We incorporate by reference the documents
listed below and any future filings made with the SEC under Sections 13(a),
13(c), 14 or 15(d) of the Securities Exchange Act of 1934,
excluding any
information furnished to the SEC pursuant to Item 2.02 or Item 7.01 of any
current report on Form 8-K (or any exhibits that are furnished and not filed
pursuant to Item 9.01 of such Form) and any certification furnished to the SEC
as an exhibit to any periodic report on Form 10-K or Form 10-Q
.  The
documents we are incorporating by reference as of their respective dates of
filing are:
•
Current
Report on Form 8-K, filed January 7, 2005, announcing the departure of the CFO
and the appointment of a new principal financial and accounting officer (File No. 000-17999);
•
Current
Report on Form 8-K, filed December 28, 2004, announcing a material definitive
agreement (File No. 000-17999);
•
Quarterly
Report on Form 10-Q for the period ended September 30, 2004, filed on November
9, 2004 (File No. 000-17999);
•
Additional
Soliciting Materials relating to the Definitive Proxy Statement for Annual
Meeting of Stockholders on Schedule 14A, filed on November 4, 2004 (File No.
000-17999);
•
Current
Report on Form 8-K, filed October 27, 2004, announcing the departure of the
registrant's Vice President, Finance and Treasurer and the appointment of a new
CFO (File No. 000-17999);
•
Current
Report on Form 8-K, filed October 6, 2004, announcing a material definitive
agreement (File No. 000-17999);
•
Definitive
Proxy Statement for Annual Meeting of Stockholders on Schedule 14A, filed on
October 6, 2004 (File No. 000-17999);
•
Our
Annual Report on Form 10-K for the year ended June 30, 2004, filed on August
20, 2004 (File No. 000-17999); and
•
The description of the Company's
capital stock contained in the Company's registration statement on Form 8-A
under the Exchange Act (File No. 000-17999), including amendments or reports
filed for the purpose of updating such description.
You may request, orally or
in writing, a copy of these filings, which will be provided to you at no cost,
by contacting Mitchel Sayare, President, Chief Executive Officer and Chairman
of the Board, ImmunoGen, Inc., 128 Sidney Street, Cambridge, MA 02139,
(617) 995-2500.
To
the extent that any statements contained in a document incorporated by
reference are modified or superceded by any statements contained in this
prospectus, such statements shall not be deemed incorporated in this prospectus
except as so modified or superceded.
All
documents subsequently filed by us pursuant to Sections 13(a), 13(c), 14 or
15(d) of the Exchange Act and prior to the termination of this offering (
other than any
information furnished and not filed with the SEC on any current report on Form
8-K or any exhibits furnished pursuant to Item 9.01 of such Form) and other
than any certification furnished to the SEC as an exhibit to any periodic report
on Form 10-K or Form 10-Q)
are incorporated by reference and become a
part of this prospectus from the date such documents are filed. Any statement
contained in this
3
prospectus
or in a document incorporated by reference is modified or superceded for
purposes of this prospectus to the extent that a statement contained in any
subsequent filed document modifies or supercedes such statement.
Item 4.  Description of Securities
.
Not applicable.
Item 5.  Interests of Named Experts and Counsel
.
Members of Mintz, Levin,
Cohn, Ferris, Glovsky and Popeo, P.C. beneficially own no shares of Common
Stock of the Company.
Item 6.  Indemnification of Directors and Officers
.
Article 6(d) of
ImmunoGen, Inc.'s Restated Articles of Organization provides as follows:
"(d)
The liability of the Directors of the Corporation shall be limited to the
fullest extent permitted by Section 13(b)(1
1
/
2
) of the Massachusetts Business
Corporation Law."
Section 6.6
of the ImmunoGen, Inc.'s By-Laws provides as follows:
"Section 6.6
Indemnification of Officers, Directors, and Members of the Scientific Advisory
Board. The corporation shall indemnify and hold harmless each person, now or
hereafter an officer or Director of the corporation, or a member of the
Scientific Advisory Board, from and against any and all claims and liabilities
to which he may be or become subject by reason of his being or having been an
officer, Director or member of the Scientific Advisory Board of the corporation
or by reason of his alleged acts or omissions as an officer, Director or member
of the Scientific Advisory Board of the corporation, and shall indemnify and
reimburse each such officer, Director and member of the Scientific Advisory
Board against and for any and all legal and other expenses reasonably incurred
by him in connection with any such claims and liabilities, actual or
threatened, whether or not at or prior to the time which so indemnified, held
harmless and reimbursed he has ceased to be an officer, Director or member of
the Scientific Advisory Board of the corporation, except with respect to any
matter as to which such officer, Director or member of the Scientific Advisory
Board of the corporation shall have been adjudicated in any proceeding not to
have acted in good faith in the reasonable belief that his action was in the
best interest of the corporation; provided, however, that prior to such final
adjudication the corporation may compromise and settle any such claims and
liabilities and pay such expenses, if such settlement or payment or both
appears, in the judgment of a majority of those members of the Board of
Directors who are not involved in such matters, to be for the best interest of
the corporation as evidenced by a resolution to that effect adopted after
receipt by the corporation of a written opinion of counsel for the corporation,
that, based on the facts available to such counsel, such officer, Director or
member of the Scientific Advisory Board of the corporation has not been guilty
of acting in a manner that would prohibit indemnification.
Such
indemnification may include payment by the corporation of expenses incurred in
defending a civil or criminal action or proceeding in advance of the final
disposition of such action or proceeding, upon receipt of an undertaking by the
person indemnified to repay such payment if he shall be adjudicated not to be
entitled to indemnification under this section.
The
corporation shall similarly indemnify and hold harmless persons who serve at
its express written request as directors or officers of another organization in
which the corporation owns shares or of which it is a creditor.
The
right of indemnification herein provided shall be in addition to and not
exclusive of any other rights to which any officer, Director or member of the
Scientific Advisory Board of the corporation, or any such persons who serve at
its request as aforesaid, may otherwise be lawfully entitled. As used in this
Section, the terms "officer,"
4
"Director," and "member
of the Scientific Advisory Board" include their respective heirs, executors,
and administrators."
Item 7.  Exemption from Registration Claimed
.
Not applicable.
Item 8.  Exhibits
.
(3.1)
Restated Articles of
  Organization of the Registrant (previously filed as Exhibit 3.1 to the
  Registrant's Quarterly Report on Form 10-Q for the quarter ended
  September 30, 1996, File No. 0-17999, and incorporated herein by
  reference).
(3.2)
Amendment to Articles
  of Organization of the Registrant (previously filed as Exhibit 3.1 to
  the Registrant's Quarterly Report on Form 10-Q for the quarter ended
  December 31, 2001, File No. 0-17999, and incorporated herein by
  reference).
(3.3)
By-laws of the
  Registrant, as amended (previously filed as Exhibit 3.2 to the
  Registrant's Annual Report on Form 10-K for the fiscal year ended
  June 30, 1990, File No. 0-17999, and incorporated herein by
  reference).
(4.1)
Form of Common Stock Certificate (previously filed
  as Exhibit 4.2 to the Registrant's Registration Statement on
  Form S-1, File No. 333-31219, and incorporated herein by
  reference).
(5)
Opinion of Mintz,
  Levin, Cohn, Ferris, Glovsky and Popeo, P.C. as to the legality of shares
  being registered.
(23.1)
Consent of Mintz, Levin, Cohn, Ferris, Glovsky and
  Popeo, P.C. (included in opinion of counsel filed as Exhibit 5).
(23.2)
Consent of Ernst &
  Young LLP.
(24)
Power of Attorney
  (included on the signature page of the Registration Statement).
(99.1)
ImmunoGen, Inc.
  Restated Stock Option Plan as amended on February 2, 2005.
Item 9.  Undertakings
.
(a)
The
undersigned Registrant hereby undertakes:
(1)
To
file, during any period in which offers or sales are being made, a
post-effective amendment to this Registration Statement:
(i)
To
include any prospectus required by Section 10(a)(3) of the Securities Act of
1933;
(ii)
To
reflect in the prospectus any facts or events arising after the effective date
of the Registration Statement (or the most recent post-effective amendment
thereof) which, individually or in the aggregate, represents a fundamental
change in the information set forth in the Registration Statement.  Notwithstanding the foregoing, any increase or
decrease in volume of securities offered (if
5
the
total dollar value of securities offered would not exceed that which was
registered) and any deviation from the low or high end of the estimated maximum
offering range may be reflected in the form of prospectus filed with the
Commission pursuant to Rule 424(b) (Section 230.424(b) of this chapter) if, in
the aggregate, the changes in volume and price represent no more than a 20%
change in the maximum aggregate offering price set forth in the "Calculation of
Registration Fee" table in the effective Registration Statement.
(iii)
To include any material
information with respect to the plan of distribution not previously disclosed
in the Registration Statement or any material change to such information in the
Registration Statement;
Provided, however
, that
paragraphs (a)(1)(i) and (a)(1)(ii) do not apply if the Registration Statement
is on Form S-3, Form S-8 or Form F-3, and the information required to be
included in a post-effective amendment by those paragraphs is contained in
periodic reports filed with or furnished to the Commission by the Registrant
pursuant to Section 13 or Section 15(d) of the Securities Exchange Act of 1934
that are incorporated by reference in this Registration Statement.
(2)
That,
for the purpose of determining any liability under the Securities Act of 1933,
each such post-effective amendment shall be deemed to be a new registration
statement relating to the securities offered therein, and the offering of such
securities at that time shall be deemed to be the initial bona fide offering
thereof.
(3)
To
remove from registration by means of a post-effective amendment any of the
securities being registered which remain unsold at the termination of the
offering.
(b)
The
undersigned Registrant hereby undertakes that, for purposes of determining any
liability under the Securities Act of 1933, each filing of the Registrant's
annual report pursuant to Section 13(a) or Section 15(d) of the Securities
Exchange Act of 1934 that is incorporated by reference in this Registration
Statement shall be deemed to be a new registration statement relating to the
securities offered therein, and the offering of such securities at that time
shall be deemed to be the initial bona fide offering thereof.
(c)
Insofar
as indemnification for liabilities arising under the Securities Act of 1933 may
be permitted to directors, officers and controlling persons of the Registrant
pursuant to the foregoing provisions, or otherwise, the Registrant has been
advised that in the opinion of the Securities and Exchange Commission such
indemnification is against public policy as expressed in the Act and is,
therefore, unenforceable.  In the event
that a claim for indemnification against such liabilities (other than the payment
by the Registrant of expenses incurred or paid by a director, officer or
controlling person of the Registrant in the successful defense of any action,
suit or proceeding) is asserted by such director, officer or controlling person
in connection with the securities being registered, the Registrant will, unless
in the opinion of its counsel the matter has been settled by controlling
precedent, submit to a court of appropriate jurisdiction the question whether
such indemnification by it is against public policy as expressed in the Act and
will be governed by the final adjudication of such issue.
6
SIGNATURES
Pursuant to the
requirements of the Securities Act of 1933, the Registrant certifies that it
has reasonable grounds to believe that it meets all of the requirements for
filing on Form S-8 and has duly caused this Registration Statement to be signed
on its behalf by the undersigned, thereunto duly authorized, in Cambridge,
Massachusetts on February 4, 2005.
IMMUNOGEN, INC.
By:
/s/ Mitchel Sayare
Chairman of the Board
  of Directors, President and Chief
Executive Officer (principal executive officer)
Each person whose
signature appears below constitutes and appoints Mitchel Sayare, and each of
them, his or her true and lawful attorneys-in-fact and agents, with full power
of substitution and resubstitution in each of them, for him or her and in his
or her name, place and stead, and in any and all capacities, to sign any and
all amendments (including post-effective amendments) to this Registration
Statement on Form S-8 of ImmunoGen, Inc., and to file the same, with all
exhibits thereto and other documents in connection therewith, with the
Securities and Exchange Commission, granting unto said attorneys-in-fact and
agents, and each of them, full power and authority to do and perform each and
every act and thing requisite or necessary to be done in or about the premises,
as full to all intents and purposes as he or she might or could do in person,
hereby ratifying and confirming all that said attorneys-in-fact and agents or
any of them or their or his or her substitute or substitutes may lawfully do or
cause to be done by virtue hereof.
Pursuant to the requirements of the Securities Act of
1933, this Registration Statement has been signed by the following persons in
the capacities and on the dates indicated.
SIGNATURE
TITLE
DATE
/s/ MITCHEL
  SAYARE
Chairman of the Board
  of
Mitchel Sayare
Directors, President
  and Chief
Executive Officer (principal
executive officer)
February 4, 2005
/s/ WALTER A.
  BLÄTTLER
Executive Vice
  President, Science
and Technology and Director
February 4, 2005
Walter A.
  Blättler
/s/ KARLEEN M.
  OBERTON
Senior Corporate
  Controller
(principal financial and accounting
officer)
February 4, 2005
Karleen M.
  Oberton
/s/ DAVID W.
  CARTER
Director
February 4, 2005
David W. Carter
7
/s/ STUART F.
  FEINER
Director
February 4, 2005
Stuart F. Feiner
/s/ MARK
  SKALETSKY
Director
February 4, 2005
Mark Skaletsky
/s/ JOSEPH J.
  VILLAFRANCA
Director
February 4, 2005
Joseph J.
  Villafranca
8
IMMUNOGEN, INC.
INDEX TO EXHIBITS
FILED WITH
FORM S-8
REGISTRATION STATEMENT
Exhibit
Number
Description
5
Opinion of Mintz,
  Levin, Cohn, Ferris, Glovsky and Popeo, P.C. as to the legality of shares
  being registered.
23.1
Consent of Mintz, Levin,
  Cohn, Ferris, Glovsky and Popeo, P.C (included in opinion of counsel filed as
  Exhibit 5).
23.2
Consent of Ernst &
  Young LLP.
24
Power of Attorney
  (included on the signature page of the Registration Statement).
99.1
ImmunoGen, Inc. Restated
  Stock Option Plan as amended on February 2, 2005.
9