<PAGE>   1
              As filed with the Securities and Exchange Commission
                                  June 16, 1997
                                                  Registration No. 333-
================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                    FORM S-8

                          REGISTRATION STATEMENT UNDER
                           THE SECURITIES ACT OF 1933



                        MILLENNIUM PHARMACEUTICALS, INC.
             (Exact name of registrant as specified in its charter)

          DELAWARE                                           04-3177038
(State or other jurisdiction of                           (I.R.S. Employer
incorporation or organization)                          Identification Number)

                               640 MEMORIAL DRIVE
                         CAMBRIDGE, MASSACHUSETTS 02139
               (Address of Principal Executive Offices) (Zip Code)


                           1997 EQUITY INCENTIVE PLAN
                            (Full title of the plan)


                                  MARK J. LEVIN
                             CHIEF EXECUTIVE OFFICER
                        MILLENNIUM PHARMACEUTICALS, INC.
                               640 MEMORIAL DRIVE
                         CAMBRIDGE, MASSACHUSETTS 02139
                     (NAME AND ADDRESS OF AGENT FOR SERVICE)

                                 (617) 679-7000
          (Telephone number, including area code, of agent for service)


<TABLE>
                                                  CALCULATION OF REGISTRATION FEE
====================================================================================================================================
<CAPTION>
                                                              Proposed                     Proposed
    Title of Securities            Amount to be           maximum offering            maximum aggregate               Amount of
     to be Registered               Registered             price per share              offering price             registration fee
------------------------------------------------------------------------------------------------------------------------------------
<S>                             <C>                            <C>                      <C>                           <C>       
Common Stock,
$.001 par value                 2,000,000 shares(1)            $16.25(2)                $32,500,000(2)                $9,849(3)
====================================================================================================================================

--------------------------
<FN>
(1)  To be offered by the Registrant pursuant to the Plan described herein.
(2)  Estimated solely for the purpose of calculating the registration fee, and
     based upon the average of the high and low prices of the Registrant's
     Common Stock on the Nasdaq National Market on June 11, 1997 in accordance
     with Rules 457(c) and 457(h) of the Securities Act of 1933.
(3)  Computed in accordance with Securities Act Rules 457(c) and (h).

</TABLE>


<PAGE>   2




PART I.  INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

     The information required by Part I is included in documents sent or given
to participants in the 1997 Equity Incentive Plan of Millennium Pharmaceuticals,
Inc., a Delaware corporation (the "Registrant") pursuant to Rule 428(b)(1) of
the Securities Act of 1933, as amended (the "Securities Act").

PART II.  INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

     Item 3. Incorporation of Certain Documents by Reference.
             -----------------------------------------------

     The Registrant is subject to the informational and reporting requirements
of Sections 13(a), 14 and 15(d) of the Securities Exchange Act of 1934, as
amended (the "Exchange Act"), and in accordance therewith files reports, proxy
statements and other information with the Securities and Exchange Commission
(the "Commission"). The following documents, which are filed with the
Commission, are incorporated in this Registration Statement by reference:

               (1)  The Registrant's latest annual report filed pursuant to
                    Section 13(a) or 15(d) of the Exchange Act, or the latest
                    prospectus filed pursuant to Rule 424(b) under the
                    Securities Act that contains, either directly or by
                    incorporation by reference, audited financial statements for
                    the Registrant's latest fiscal year for which such
                    statements have been filed.

               (2)  All other reports filed pursuant to Section 13(a) or 15(d)
                    of the Exchange Act since the end of the fiscal year covered
                    by the document referred to in (1) above.

               (3)  The description of the Common Stock, par value $.001 per
                    share ("Common Stock"), contained in the Registrant's
                    Registration Statement on Form 8-A filed under the Exchange
                    Act, including any amendment or report filed for the purpose
                    of updating such description.

     All documents subsequently filed by the Registrant pursuant to Sections
13(a), 13(c), 14 and 15(d) of the Exchange Act prior to the filing of a
post-effective amendment which indicates that all shares of Common Stock offered
hereby have been sold or which deregisters all shares of Common Stock then
remaining unsold, shall be deemed to be incorporated by reference herein and to
be part hereof from the date of the filing of such documents.



<PAGE>   3




     Item 4. Description of Securities.
             -------------------------

     Not applicable.

     Item 5. Interests of Named Experts and Counsel.
             --------------------------------------

     Not applicable.

     Item 6. Indemnification of Directors and Officers.
             -----------------------------------------

     Article EIGHTH of the Registrant's Amended and Restated Certificate of
Incorporation provides that no director of the Registrant shall be personally
liable for any monetary damages for any breach of fiduciary duty as a director,
except to the extent that the Delaware General Corporation Law prohibits the
elimination or limitation of liability of directors for breach of fiduciary
duty.

     Article NINTH of the Registrant's Amended and Restated Certificate of
Incorporation provides that a director or officer of the Registrant (a) shall be
indemnified by the Registrant against all expenses (including attorneys' fees),
judgments, fines and amounts paid in settlement incurred in connection with any
litigation or other legal proceeding (other than an action by or in the right of
the Registrant) brought against him by virtue of his position as a director or
officer of the Registrant if he acted in good faith and in a manner he
reasonably believed to be in, or not opposed to, the best interests of the
Registrant, and, with respect to any criminal action or proceeding, has no
reasonable cause to believe his conduct was unlawful and (b) shall be
indemnified by the Registrant against all expenses (including attorneys' fees)
and amounts paid in settlement incurred in connection with any action by or in
the right of the Registrant brought against him by virtue of his position as a
director or officer of the Registrant if he acted in good faith and in a manner
he reasonably believed to be in, or not opposed to, the best interests of the
Registrant, except that no indemnification shall be made with respect to any
matter as to which such person shall have been adjudged to be liable to the
Registrant, unless a court determines that, despite such adjudication but in
view of all of the circumstances, he is entitled to indemnification of such
expenses. Notwithstanding the foregoing, to the extent that a director or
officer has been successful, on the merits or otherwise, including, without
limitation, the dismissal of an action without prejudice, he is required to be
indemnified by the Registrant against all expenses (including attorneys' fees)
incurred in connection therewith. Expenses shall be advanced to a Director or
officer at his request, provided that he undertakes to repay the amount advanced
if it is ultimately determined that he is not entitled to indemnification for
such expenses.


                                      - 2 -

<PAGE>   4




     Indemnification is required to be made promptly unless the Registrant
determines that the applicable standard of conduct required for indemnification
has not been met. In the event the Registrant denies a request for
indemnification, or if the Registrant fails to dispose of a request for
indemnification within 60 days after such payment is claimed by the indemnitee,
such person is permitted to petition the court to make an independent
determination as to whether such person is entitled to indemnification. As a
condition precedent to the right of indemnification, the director or officer
must give the Registrant notice of the action for which indemnity is sought and
the Registrant has the right to participate in such action or assume the defense
thereof.

     Article NINTH of the Registrant's Amended and Restated Certificate of
Incorporation further provides that the indemnification provided therein is not
exclusive.

     Section 145 of the Delaware General Corporation Law provides that a
corporation has the power to indemnify a director, officer, employee or agent of
the corporation and certain other persons serving at the request of the
corporation in related capacities against amounts paid and expenses incurred in
connection with an action or proceeding to which he is or is threatened to be
made a party by reason of such position, if such person shall have acted in good
faith and in a manner he reasonably believed to be in or not opposed to the best
interests of the corporation, and, in any criminal proceeding, if such person
had no reasonable cause to believe his conduct was unlawful; provided that, in
the case of actions brought by or in the right of the corporation no
indemnification shall be made with respect to any matter as to which such person
shall have been adjudged to be liable to the corporation unless and only to the
extent that the adjudicating court determines that such indemnification is
proper under the circumstances.

     Item 7. Exemption from Registration Claimed.
             -----------------------------------

     Not applicable.

     Item 8. Exhibits.
             --------

     The Exhibit Index immediately preceding the exhibits is incorporated herein
by reference.


                                      - 3 -

<PAGE>   5




     Item 9. Undertakings.
             ------------

     1.   The Registrant hereby undertakes:

          (a)  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;

               (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, represent 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 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) 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; and

               (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 (i) and (ii) do not apply if
               the registration statement is on Form S-3 or Form S-8, and the
               information required to be included in a post-effective amendment
               by those paragraphs is contained in periodic reports filed by the
               Registrant pursuant to Section 13(a) or Section 15(d) of the
               Exchange Act that are incorporated by reference in the
               registration statement.

          (b)  That, for the purpose of determining any liability under the
               Securities Act, each such post-effective amendment shall be

                                      - 4 -

<PAGE>   6


               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)  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.

     2. The Registrant hereby undertakes that, for purposes of determining any
liability under the Securities Act, each filing of the Registrant's annual
report pursuant to Section 13(a) or Section 15(d) of the Exchange Act (and,
where applicable, each filing of an employee benefit plan's annual report
pursuant to Section 15(d) of the Exchange Act) that is incorporated by reference
in the 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.

     3. Insofar as indemnification for liabilities arising under the Securities
Act 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 Commission such indemnification is
against public policy as expressed in the Securities 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 Securities Act and will be governed by the final
adjudication of such issue.



                                      - 5 -

<PAGE>   7





                                   SIGNATURES

     Pursuant to the requirements of the Securities Act, 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 the City of Cambridge, Commonwealth of Massachusetts on the 16th
day of June, 1997.


                                        MILLENNIUM PHARMACEUTICALS, INC.



                                        By:  /s/ Mark J. Levin
                                             --------------------------------
                                             Mark J. Levin
                                             Chief Executive Officer



                                POWER OF ATTORNEY

     We, the undersigned officers and directors of Millennium Pharmaceuticals,
Inc. hereby severally constitute Mark J. Levin, Steven H. Holtzman and Steven D.
Singer, and each of them singly, our true and lawful attorneys with full power
to them, and each of them singly, to sign for us and in our names in the
capacities indicated below, the Registration Statement on Form S-8 filed
herewith and any and all subsequent amendments to said Registration Statement,
and generally to do all such things in our names and behalf in our capacities as
officers and directors to enable Millennium Pharmaceuticals, Inc. to comply with
all requirements of the Commission, hereby ratifying and confirming our
signatures as they may be signed by said attorneys, or any of them, to said
Registration Statement and any and all amendments thereto.


                                      - 6 -

<PAGE>   8




     Pursuant to the requirements of the Securities Act, this Registration
Statement has been signed below by the following persons in the capacities and
on the dates indicated.


       Signature                           Title                       Date
       ---------                           -----                       ----

/s/ Mark J. Levin                 Chief Executive Officer and      June 16, 1997
----------------------------      Director (Principal Executive
Mark J. Levin                     Officer)                     
                                  
/s/ Steven H. Holtzman            Chief Business Officer           June 16, 1997
----------------------------      (Principal Financial 
Steven H. Holtzman                Officer)     

/s/ Peter J. Courossi             Director of Finance              June 16, 1997
----------------------------      (Principal Accounting 
Peter J. Courossi                 Officer)     
                                  
/s/ Joshua Boger                  Director                         June 16, 1997
----------------------------
Joshua Boger

/s/ Eugene Cordes                 Director                         June 16, 1997
----------------------------
Eugene Cordes

/s/ A. Grant Heidrich, III        Director                         June 16, 1997
----------------------------  
A. Grant Heidrich, III

/s/ William W. Helman             Director                         June 16, 1997
----------------------------
William W. Helman

/s/ Raju Kucherlapati             Director                         June 16, 1997
----------------------------  
Raju Kucherlapati

/s/ Eric Lander                   Director                         June 16, 1997
----------------------------    
Eric Lander



                                      - 7 -

<PAGE>   9




                                  EXHIBIT INDEX



Exhibit Number                        Description
--------------                        -----------

      4.1           Amended and Restated Certificate of Incorporation of the
                    Registrant (incorporated herein by reference to Exhibit 4.1
                    to the Registrant's Quarterly Report on Form 10-Q, filed
                    June 20, 1996).

      4.2           Restated By-Laws of the Registrant (incorporated herein by
                    reference to Exhibit 4.2 to the Registrant's Quarterly
                    Report on Form 10-Q, filed June 20, 1996).

      4.3           Specimen Certificate representing shares of the Registrant's
                    $.001 par value Common Stock (incorporated herein by
                    reference to Exhibit 4.1 to Amendment No. 2 to the
                    Registrant's Registration Statement on Form S-1, filed May
                    2, 1996).

      5.1*          Opinion of Hale and Dorr LLP.

     23.2*          Consent of Ernst & Young LLP.

     23.3*          Consent of Arthur Andersen LLP.

     24.1*          Consent of Hale and Dorr LLP (included in Exhibit 5.1).

     25.1*          Power of Attorney (see signature pages of this Registration
                    Statement).

---------------
*  Filed herewith.  All other exhibits previously filed.
[{"type": "S-8", "sequence": "1", "description": "MILLENNIUM PHARMACEUTICALS, INC.", "secsgml_size_bytes": 20767}]
{"company-data": {"conformed-name": "MILLENNIUM PHARMACEUTICALS INC", "cik": "0001002637", "assigned-sic": "2834", "irs-number": "043177038", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-29319", "film-number": "97624850"}, "business-address": {"street1": "640 MEMORIAL DR", "city": "CAMBRIDGE", "state": "MA", "zip": "02139", "phone": "6176797000"}}
1
              As filed with the Securities and Exchange Commission
                                  June 16, 1997
                                                  Registration No. 333-
================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                    FORM S-8

                          REGISTRATION STATEMENT UNDER
                           THE SECURITIES ACT OF 1933

                        MILLENNIUM PHARMACEUTICALS, INC.
             (Exact name of registrant as specified in its charter)

          DELAWARE                                           04-3177038
(State or other jurisdiction of                           (I.R.S. Employer
incorporation or organization)                          Identification Number)

                               640 MEMORIAL DRIVE
                         CAMBRIDGE, MASSACHUSETTS 02139
               (Address of Principal Executive Offices) (Zip Code)

                           1997 EQUITY INCENTIVE PLAN
                            (Full title of the plan)

                                  MARK J. LEVIN
                             CHIEF EXECUTIVE OFFICER
                        MILLENNIUM PHARMACEUTICALS, INC.
                               640 MEMORIAL DRIVE
                         CAMBRIDGE, MASSACHUSETTS 02139
                     (NAME AND ADDRESS OF AGENT FOR SERVICE)

                                 (617) 679-7000
          (Telephone number, including area code, of agent for service)

                                                  CALCULATION OF REGISTRATION FEE
====================================================================================================================================
Proposed                     Proposed
    Title of Securities            Amount to be           maximum offering            maximum aggregate               Amount of
     to be Registered               Registered             price per share              offering price             registration fee
------------------------------------------------------------------------------------------------------------------------------------
Common Stock,
$.001 par value                 2,000,000 shares(1)            $16.25(2)                $32,500,000(2)                $9,849(3)
====================================================================================================================================

--------------------------
(1)  To be offered by the Registrant pursuant to the Plan described herein.
(2)  Estimated solely for the purpose of calculating the registration fee, and
     based upon the average of the high and low prices of the Registrant's
     Common Stock on the Nasdaq National Market on June 11, 1997 in accordance
     with Rules 457(c) and 457(h) of the Securities Act of 1933.
(3)  Computed in accordance with Securities Act Rules 457(c) and (h).
2

PART I.  INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

     The information required by Part I is included in documents sent or given
to participants in the 1997 Equity Incentive Plan of Millennium Pharmaceuticals,
Inc., a Delaware corporation (the "Registrant") pursuant to Rule 428(b)(1) of
the Securities Act of 1933, as amended (the "Securities Act").

PART II.  INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

     Item 3. Incorporation of Certain Documents by Reference.
             -----------------------------------------------

     The Registrant is subject to the informational and reporting requirements
of Sections 13(a), 14 and 15(d) of the Securities Exchange Act of 1934, as
amended (the "Exchange Act"), and in accordance therewith files reports, proxy
statements and other information with the Securities and Exchange Commission
(the "Commission"). The following documents, which are filed with the
Commission, are incorporated in this Registration Statement by reference:

               (1)  The Registrant's latest annual report filed pursuant to
                    Section 13(a) or 15(d) of the Exchange Act, or the latest
                    prospectus filed pursuant to Rule 424(b) under the
                    Securities Act that contains, either directly or by
                    incorporation by reference, audited financial statements for
                    the Registrant's latest fiscal year for which such
                    statements have been filed.

               (2)  All other reports filed pursuant to Section 13(a) or 15(d)
                    of the Exchange Act since the end of the fiscal year covered
                    by the document referred to in (1) above.

               (3)  The description of the Common Stock, par value $.001 per
                    share ("Common Stock"), contained in the Registrant's
                    Registration Statement on Form 8-A filed under the Exchange
                    Act, including any amendment or report filed for the purpose
                    of updating such description.

     All documents subsequently filed by the Registrant pursuant to Sections
13(a), 13(c), 14 and 15(d) of the Exchange Act prior to the filing of a
post-effective amendment which indicates that all shares of Common Stock offered
hereby have been sold or which deregisters all shares of Common Stock then
remaining unsold, shall be deemed to be incorporated by reference herein and to
be part hereof from the date of the filing of such documents.
3

     Item 4. Description of Securities.
             -------------------------

     Not applicable.

     Item 5. Interests of Named Experts and Counsel.
             --------------------------------------

     Not applicable.

     Item 6. Indemnification of Directors and Officers.
             -----------------------------------------

     Article EIGHTH of the Registrant's Amended and Restated Certificate of
Incorporation provides that no director of the Registrant shall be personally
liable for any monetary damages for any breach of fiduciary duty as a director,
except to the extent that the Delaware General Corporation Law prohibits the
elimination or limitation of liability of directors for breach of fiduciary
duty.

     Article NINTH of the Registrant's Amended and Restated Certificate of
Incorporation provides that a director or officer of the Registrant (a) shall be
indemnified by the Registrant against all expenses (including attorneys' fees),
judgments, fines and amounts paid in settlement incurred in connection with any
litigation or other legal proceeding (other than an action by or in the right of
the Registrant) brought against him by virtue of his position as a director or
officer of the Registrant if he acted in good faith and in a manner he
reasonably believed to be in, or not opposed to, the best interests of the
Registrant, and, with respect to any criminal action or proceeding, has no
reasonable cause to believe his conduct was unlawful and (b) shall be
indemnified by the Registrant against all expenses (including attorneys' fees)
and amounts paid in settlement incurred in connection with any action by or in
the right of the Registrant brought against him by virtue of his position as a
director or officer of the Registrant if he acted in good faith and in a manner
he reasonably believed to be in, or not opposed to, the best interests of the
Registrant, except that no indemnification shall be made with respect to any
matter as to which such person shall have been adjudged to be liable to the
Registrant, unless a court determines that, despite such adjudication but in
view of all of the circumstances, he is entitled to indemnification of such
expenses. Notwithstanding the foregoing, to the extent that a director or
officer has been successful, on the merits or otherwise, including, without
limitation, the dismissal of an action without prejudice, he is required to be
indemnified by the Registrant against all expenses (including attorneys' fees)
incurred in connection therewith. Expenses shall be advanced to a Director or
officer at his request, provided that he undertakes to repay the amount advanced
if it is ultimately determined that he is not entitled to indemnification for
such expenses.

                                      - 2 -
4

     Indemnification is required to be made promptly unless the Registrant
determines that the applicable standard of conduct required for indemnification
has not been met. In the event the Registrant denies a request for
indemnification, or if the Registrant fails to dispose of a request for
indemnification within 60 days after such payment is claimed by the indemnitee,
such person is permitted to petition the court to make an independent
determination as to whether such person is entitled to indemnification. As a
condition precedent to the right of indemnification, the director or officer
must give the Registrant notice of the action for which indemnity is sought and
the Registrant has the right to participate in such action or assume the defense
thereof.

     Article NINTH of the Registrant's Amended and Restated Certificate of
Incorporation further provides that the indemnification provided therein is not
exclusive.

     Section 145 of the Delaware General Corporation Law provides that a
corporation has the power to indemnify a director, officer, employee or agent of
the corporation and certain other persons serving at the request of the
corporation in related capacities against amounts paid and expenses incurred in
connection with an action or proceeding to which he is or is threatened to be
made a party by reason of such position, if such person shall have acted in good
faith and in a manner he reasonably believed to be in or not opposed to the best
interests of the corporation, and, in any criminal proceeding, if such person
had no reasonable cause to believe his conduct was unlawful; provided that, in
the case of actions brought by or in the right of the corporation no
indemnification shall be made with respect to any matter as to which such person
shall have been adjudged to be liable to the corporation unless and only to the
extent that the adjudicating court determines that such indemnification is
proper under the circumstances.

     Item 7. Exemption from Registration Claimed.
             -----------------------------------

     Not applicable.

     Item 8. Exhibits.
             --------

     The Exhibit Index immediately preceding the exhibits is incorporated herein
by reference.

                                      - 3 -
5

     Item 9. Undertakings.
             ------------

     1.   The Registrant hereby undertakes:

          (a)  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;

               (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, represent 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 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) 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; and

               (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 (i) and (ii) do not apply if
               the registration statement is on Form S-3 or Form S-8, and the
               information required to be included in a post-effective amendment
               by those paragraphs is contained in periodic reports filed by the
               Registrant pursuant to Section 13(a) or Section 15(d) of the
               Exchange Act that are incorporated by reference in the
               registration statement.

          (b)  That, for the purpose of determining any liability under the
               Securities Act, each such post-effective amendment shall be

                                      - 4 -
6

               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)  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.

     2. The Registrant hereby undertakes that, for purposes of determining any
liability under the Securities Act, each filing of the Registrant's annual
report pursuant to Section 13(a) or Section 15(d) of the Exchange Act (and,
where applicable, each filing of an employee benefit plan's annual report
pursuant to Section 15(d) of the Exchange Act) that is incorporated by reference
in the 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.

     3. Insofar as indemnification for liabilities arising under the Securities
Act 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 Commission such indemnification is
against public policy as expressed in the Securities 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 Securities Act and will be governed by the final
adjudication of such issue.

                                      - 5 -
7

                                   SIGNATURES

     Pursuant to the requirements of the Securities Act, 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 the City of Cambridge, Commonwealth of Massachusetts on the 16th
day of June, 1997.

                                        MILLENNIUM PHARMACEUTICALS, INC.

                                        By:  /s/ Mark J. Levin
                                             --------------------------------
                                             Mark J. Levin
                                             Chief Executive Officer

                                POWER OF ATTORNEY

     We, the undersigned officers and directors of Millennium Pharmaceuticals,
Inc. hereby severally constitute Mark J. Levin, Steven H. Holtzman and Steven D.
Singer, and each of them singly, our true and lawful attorneys with full power
to them, and each of them singly, to sign for us and in our names in the
capacities indicated below, the Registration Statement on Form S-8 filed
herewith and any and all subsequent amendments to said Registration Statement,
and generally to do all such things in our names and behalf in our capacities as
officers and directors to enable Millennium Pharmaceuticals, Inc. to comply with
all requirements of the Commission, hereby ratifying and confirming our
signatures as they may be signed by said attorneys, or any of them, to said
Registration Statement and any and all amendments thereto.

                                      - 6 -
8

     Pursuant to the requirements of the Securities Act, this Registration
Statement has been signed below by the following persons in the capacities and
on the dates indicated.

       Signature                           Title                       Date
       ---------                           -----                       ----

/s/ Mark J. Levin                 Chief Executive Officer and      June 16, 1997
----------------------------      Director (Principal Executive
Mark J. Levin                     Officer)                     
                                  
/s/ Steven H. Holtzman            Chief Business Officer           June 16, 1997
----------------------------      (Principal Financial 
Steven H. Holtzman                Officer)     

/s/ Peter J. Courossi             Director of Finance              June 16, 1997
----------------------------      (Principal Accounting 
Peter J. Courossi                 Officer)     
                                  
/s/ Joshua Boger                  Director                         June 16, 1997
----------------------------
Joshua Boger

/s/ Eugene Cordes                 Director                         June 16, 1997
----------------------------
Eugene Cordes

/s/ A. Grant Heidrich, III        Director                         June 16, 1997
----------------------------  
A. Grant Heidrich, III

/s/ William W. Helman             Director                         June 16, 1997
----------------------------
William W. Helman

/s/ Raju Kucherlapati             Director                         June 16, 1997
----------------------------  
Raju Kucherlapati

/s/ Eric Lander                   Director                         June 16, 1997
----------------------------    
Eric Lander

                                      - 7 -
9

                                  EXHIBIT INDEX

Exhibit Number                        Description
--------------                        -----------

      4.1           Amended and Restated Certificate of Incorporation of the
                    Registrant (incorporated herein by reference to Exhibit 4.1
                    to the Registrant's Quarterly Report on Form 10-Q, filed
                    June 20, 1996).

      4.2           Restated By-Laws of the Registrant (incorporated herein by
                    reference to Exhibit 4.2 to the Registrant's Quarterly
                    Report on Form 10-Q, filed June 20, 1996).

      4.3           Specimen Certificate representing shares of the Registrant's
                    $.001 par value Common Stock (incorporated herein by
                    reference to Exhibit 4.1 to Amendment No. 2 to the
                    Registrant's Registration Statement on Form S-1, filed May
                    2, 1996).

      5.1*          Opinion of Hale and Dorr LLP.

     23.2*          Consent of Ernst & Young LLP.

     23.3*          Consent of Arthur Andersen LLP.

     24.1*          Consent of Hale and Dorr LLP (included in Exhibit 5.1).

     25.1*          Power of Attorney (see signature pages of this Registration
                    Statement).

---------------
*  Filed herewith.  All other exhibits previously filed.