<PAGE>


              As filed with the Securities and Exchange Commission
                                on April 28, 2000

                                                      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)

      75 SIDNEY STREET, CAMBRIDGE, MASSACHUSETTS                   02139
       (Address of Principal Executive Offices)                  (Zip Code)

           MILLENNIUM PHARMACEUTICALS, INC. 2000 STOCK INCENTIVE PLAN
                            (Full title of the Plan)

                               JOHN B. DOUGLAS III
                                 GENERAL COUNSEL
                        MILLENNIUM PHARMACEUTICALS, INC.
                                75 SIDNEY STREET
                         CAMBRIDGE, MASSACHUSETTS 02139

                                 WITH A COPY TO:

          Steven D. Singer, Esq.                  John B. Douglas III, Esq.
            Hale and Dorr LLP                          General Counsel
             60 State Street                   Millennium Pharmaceuticals, Inc.
       Boston, Massachusetts 02109                     75 Sidney Street
              (617) 526-6000                    Cambridge, Massachusetts 02139
                                                        (617) 679-7000

             (Name, address, including zip code, and telephone number,
                    including area code, of agents for service)

                         CALCULATION OF REGISTRATION FEE
<TABLE>
<CAPTION>

==========================================================================================================
                                                Proposed Maximum       Proposed Maximum
Title of                 Amount to be           Offering Price         Aggregate              Amount of
Securities               Registered             Per Share              Offering Price         Registration
to be Registered                                                                              Fee
-------------------  ----------------------  ----------------------  ---------------------  --------------
<S>                      <C>                    <C>                    <C>                     <C>
Common Stock,
$.001 par value          4,569,774 shares       59.91(1)               273,775,161(1)          $72,277
-------------------  ----------------------  ----------------------  ---------------------  --------------
</TABLE>


<PAGE>


(1)  Estimated solely for the purpose of calculating the registration fee, and
     based upon the average of the high and low prices of the Common Stock on
     the Nasdaq National Market on April 25, 2000 in accordance with Rules
     457(c) and 457(h) of the Securities Act of 1933.



                                      -2-
<PAGE>


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 Plan 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 following documents, which are filed with the Securities and
Exchange Commission (the "Commission"), are incorporated in this Registration
Statement by reference:

              (1) The Registrant's latest annual report filed pursuant to
         Sections 13(a) or 15(d) of the Securities Exchange Act of 1934, as
         amended (the "Exchange Act"), or the latest prospectus filed pursuant
         to Rule 424(b) under the Securities Act that contains audited financial
         statements for the Registrant's latest fiscal year for which such
         statements have been filed.

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

              (3) The description of the common stock of the Registrant, $.001
         par value per share (the "Common Stock"), contained in the Registrant's
         Registration Statement on Form 8-A dated April 26, 1996 filed under the
         Exchange Act, as updated by a Current Report on Form 8-K dated April
         18, 2000, as filed with the Commission on April 25, 2000.

         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. Any statement
contained in a document incorporated or deemed to be incorporated by reference
herein shall be deemed to be modified or superseded for purposes of this
Registration Statement to the extent that a statement contained herein or in any
other subsequently filed document which also is or is deemed to be incorporated
by reference herein modifies or supersedes such statement. Any statement so
modified or superseded shall be deemed, except as so modified or superseded, to
constitute a part of this Registration Statement.

         Item 4.    DESCRIPTION OF SECURITIES

              Not applicable.

         Item 5.    INTERESTS OF NAMED EXPERTS AND COUNSEL

              Not Applicable.

         Item 6.    INDEMNIFICATION OF DIRECTORS AND OFFICERS

         Section 102 of the Delaware General Corporation Law allows a
corporation to eliminate the personal liability of directors of a corporation to
the corporation or its stockholders for monetary damages for a breach of
fiduciary duty as a director, except where the director breached his duty of
loyalty, failed to act in good faith, engaged in intentional misconduct or
knowingly violated a law, authorized the payment of a dividend or approved a
stock repurchase in violation of Delaware corporate law or obtained an improper
personal benefit. The Registrant has included such a provision in its
Certificate of Incorporation.

         Section 145 of the General Corporation Law of Delaware 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



                                      -3-
<PAGE>


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.

         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),
judgements, 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 interest 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),
judgment, fines 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 Registrants, 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.

         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.

         Item 7.    EXEMPTION FROM REGISTRATION CLAIMED

              Not applicable.

         Item 8.  EXHIBITS

<TABLE>
<CAPTION>

        Exhibit
        Number           Description
        ------------     -----------------------------------------------
        <S>              <C>
        4.1              2000 Stock Incentive Plan
        5.1              Opinion of Hale and Dorr LLP
        23.1             Consent of Hale and Dorr LLP (included in Exhibit 5.1)
        23.2             Consent of Ernst & Young LLP
        23.3             Consent of PricewaterhouseCoopers LLP
        23.4             Consent of Arthur Anderson LLP
        24.1             Power of Attorney (included on signature page to this Registration Statement)
</TABLE>



                                      -4-
<PAGE>


         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 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;

                  (b) That, for the purpose of determining any liability under
              the Securities Act, 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.

                  (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 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>


                                   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 this
28th day of April 2000.

                                          MILLENNIUM PHARMACEUTICALS, INC.

                                          By:      /s/ John B. Douglas III
                                                   --------------------------
                                          Name:    John B. Douglas III
                                          Title:   General Counsel



                                      -6-
<PAGE>


                        SIGNATURES AND POWER OF ATTORNEY

         We, the undersigned officers and directors of Millennium
Pharmaceuticals, Inc., hereby severally constitute and appoint Mark J. Levin,
Kevin P. Starr and John B. Douglas III, and each of them singly, our true and
lawful attorneys with full power to any of them, and to 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 pre-effective and
post-effective amendments to said Registration Statement and generally to do all
such things in our name and behalf in our capacities as officers and directors
to enable Millennium Pharmaceuticals, Inc. to comply with the provisions of the
Securities Act of 1933 and all requirements of the Securities and Exchange
Commission, hereby ratifying and confirming our signatures as they may be signed
by our said attorneys, or any of them, to said Registration Statement and any
and all amendments thereto.

         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 date indicated.

<TABLE>
<CAPTION>

 Signature                                 Title                                          Date
 ---------                                 -----                                          ----
<S>                                        <C>                                            <C>

   /s/ Mark J. Levin                       Chief Executive Officer and Director           April 28, 2000
--------------------------------------     (Principal Executive Officer)
   Mark J. Levin


   /s/ Kevin P. Starr                      Chief Financial Officer (Principal             April 28, 2000
 -------------------------------------     Financial and Accounting Officer)
   Kevin P. Starr


   /s/ Joshua Boger, Ph.D.                 Director                                       April 28, 2000
 -------------------------------------
   Joshua Boger, Ph.D.

   /s/ Eugene Cordes, Ph.D.                Director                                       April 28, 2000
 -------------------------------------
   Eugene Cordes, Ph.D.

   /s/ A. Grant Heidrich III               Director                                       April 28, 2000
 -------------------------------------
   A. Grant Heidrich III

    /s/ Raju S. Kucherlapti, Ph.D.         Director                                       April 28, 2000
 -------------------------------------
    Raju S. Kucherlapati, Ph.D.

   /s/ Eric S. Lander, Ph.D.               Director                                       April 28, 2000
 -------------------------------------
   Eric S. Lander, Ph.D.

   /s/ Christopher K. Mirabelli, Ph.D.     Director                                       April 28, 2000
 -------------------------------------
   Christopher K. Mirabelli, Ph.D.


   /s/ Steven C. Wheelwright, Ph.D.        Director                                       April 28, 2000
 -------------------------------------
   Steven C. Wheelwright, Ph.D.
</TABLE>



                                      -7-
<PAGE>


                                  EXHIBIT INDEX

<TABLE>
<CAPTION>
Exhibit
Number             Description
----------         ------------------------------------------------------
<S>                <C>

4.1                2000 Stock Incentive Plan
5.1                Opinion of Hale and Dorr LLP
23.1               Consent of Hale and Dorr LLP (included in Exhibit 5.1)
23.2               Consent of Ernst & Young LLP
23.3               Consent of PricewaterhouseCoopers LLP
23.4               Consent of Arthur Anderson LLP
24.1               Power of Attorney (included on the signature page to this Registration Statement)
</TABLE>



                                      -8-
[{"type": "S-8", "sequence": "1", "description": "FORM S-8", "secsgml_size_bytes": 19286}]
{"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": "333-35896", "film-number": "613505"}, "business-address": {"street1": "75 SIDNEY STREET", "city": "CAMBRIDGE", "state": "MA", "zip": "02139", "phone": "6176797000"}, "mail-address": {"street1": "640 MEMORIAL DR", "city": "CAMBRIDGE", "state": "MA", "zip": "02139"}}
As filed with the Securities and Exchange Commission
                                on April 28, 2000

                                                      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)

      75 SIDNEY STREET, CAMBRIDGE, MASSACHUSETTS                   02139
       (Address of Principal Executive Offices)                  (Zip Code)

           MILLENNIUM PHARMACEUTICALS, INC. 2000 STOCK INCENTIVE PLAN
                            (Full title of the Plan)

                               JOHN B. DOUGLAS III
                                 GENERAL COUNSEL
                        MILLENNIUM PHARMACEUTICALS, INC.
                                75 SIDNEY STREET
                         CAMBRIDGE, MASSACHUSETTS 02139

                                 WITH A COPY TO:

          Steven D. Singer, Esq.                  John B. Douglas III, Esq.
            Hale and Dorr LLP                          General Counsel
             60 State Street                   Millennium Pharmaceuticals, Inc.
       Boston, Massachusetts 02109                     75 Sidney Street
              (617) 526-6000                    Cambridge, Massachusetts 02139
                                                        (617) 679-7000

             (Name, address, including zip code, and telephone number,
                    including area code, of agents for service)

                         CALCULATION OF REGISTRATION FEE
==========================================================================================================
                                                Proposed Maximum       Proposed Maximum
Title of                 Amount to be           Offering Price         Aggregate              Amount of
Securities               Registered             Per Share              Offering Price         Registration
to be Registered                                                                              Fee
-------------------  ----------------------  ----------------------  ---------------------  --------------
Common Stock,
$.001 par value          4,569,774 shares       59.91(1)               273,775,161(1)          $72,277
-------------------  ----------------------  ----------------------  ---------------------  --------------
(1)  Estimated solely for the purpose of calculating the registration fee, and
     based upon the average of the high and low prices of the Common Stock on
     the Nasdaq National Market on April 25, 2000 in accordance with Rules
     457(c) and 457(h) of the Securities Act of 1933.

                                      -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 Plan 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 following documents, which are filed with the Securities and
Exchange Commission (the "Commission"), are incorporated in this Registration
Statement by reference:

              (1) The Registrant's latest annual report filed pursuant to
         Sections 13(a) or 15(d) of the Securities Exchange Act of 1934, as
         amended (the "Exchange Act"), or the latest prospectus filed pursuant
         to Rule 424(b) under the Securities Act that contains audited financial
         statements for the Registrant's latest fiscal year for which such
         statements have been filed.

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

              (3) The description of the common stock of the Registrant, $.001
         par value per share (the "Common Stock"), contained in the Registrant's
         Registration Statement on Form 8-A dated April 26, 1996 filed under the
         Exchange Act, as updated by a Current Report on Form 8-K dated April
         18, 2000, as filed with the Commission on April 25, 2000.

         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. Any statement
contained in a document incorporated or deemed to be incorporated by reference
herein shall be deemed to be modified or superseded for purposes of this
Registration Statement to the extent that a statement contained herein or in any
other subsequently filed document which also is or is deemed to be incorporated
by reference herein modifies or supersedes such statement. Any statement so
modified or superseded shall be deemed, except as so modified or superseded, to
constitute a part of this Registration Statement.

         Item 4.    DESCRIPTION OF SECURITIES

              Not applicable.

         Item 5.    INTERESTS OF NAMED EXPERTS AND COUNSEL

              Not Applicable.

         Item 6.    INDEMNIFICATION OF DIRECTORS AND OFFICERS

         Section 102 of the Delaware General Corporation Law allows a
corporation to eliminate the personal liability of directors of a corporation to
the corporation or its stockholders for monetary damages for a breach of
fiduciary duty as a director, except where the director breached his duty of
loyalty, failed to act in good faith, engaged in intentional misconduct or
knowingly violated a law, authorized the payment of a dividend or approved a
stock repurchase in violation of Delaware corporate law or obtained an improper
personal benefit. The Registrant has included such a provision in its
Certificate of Incorporation.

         Section 145 of the General Corporation Law of Delaware 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

                                      -3-
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.

         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),
judgements, 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 interest 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),
judgment, fines 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 Registrants, 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.

         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.

         Item 7.    EXEMPTION FROM REGISTRATION CLAIMED

              Not applicable.

         Item 8.  EXHIBITS
Exhibit
        Number           Description
        ------------     -----------------------------------------------
4.1              2000 Stock Incentive Plan
        5.1              Opinion of Hale and Dorr LLP
        23.1             Consent of Hale and Dorr LLP (included in Exhibit 5.1)
        23.2             Consent of Ernst & Young LLP
        23.3             Consent of PricewaterhouseCoopers LLP
        23.4             Consent of Arthur Anderson LLP
        24.1             Power of Attorney (included on signature page to this Registration Statement)
-4-
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 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;

                  (b) That, for the purpose of determining any liability under
              the Securities Act, 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.

                  (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 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-
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 this
28th day of April 2000.

                                          MILLENNIUM PHARMACEUTICALS, INC.

                                          By:      /s/ John B. Douglas III
                                                   --------------------------
                                          Name:    John B. Douglas III
                                          Title:   General Counsel

                                      -6-
SIGNATURES AND POWER OF ATTORNEY

         We, the undersigned officers and directors of Millennium
Pharmaceuticals, Inc., hereby severally constitute and appoint Mark J. Levin,
Kevin P. Starr and John B. Douglas III, and each of them singly, our true and
lawful attorneys with full power to any of them, and to 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 pre-effective and
post-effective amendments to said Registration Statement and generally to do all
such things in our name and behalf in our capacities as officers and directors
to enable Millennium Pharmaceuticals, Inc. to comply with the provisions of the
Securities Act of 1933 and all requirements of the Securities and Exchange
Commission, hereby ratifying and confirming our signatures as they may be signed
by our said attorneys, or any of them, to said Registration Statement and any
and all amendments thereto.

         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 date indicated.
Signature                                 Title                                          Date
 ---------                                 -----                                          ----
/s/ Mark J. Levin                       Chief Executive Officer and Director           April 28, 2000
--------------------------------------     (Principal Executive Officer)
   Mark J. Levin

   /s/ Kevin P. Starr                      Chief Financial Officer (Principal             April 28, 2000
 -------------------------------------     Financial and Accounting Officer)
   Kevin P. Starr

   /s/ Joshua Boger, Ph.D.                 Director                                       April 28, 2000
 -------------------------------------
   Joshua Boger, Ph.D.

   /s/ Eugene Cordes, Ph.D.                Director                                       April 28, 2000
 -------------------------------------
   Eugene Cordes, Ph.D.

   /s/ A. Grant Heidrich III               Director                                       April 28, 2000
 -------------------------------------
   A. Grant Heidrich III

    /s/ Raju S. Kucherlapti, Ph.D.         Director                                       April 28, 2000
 -------------------------------------
    Raju S. Kucherlapati, Ph.D.

   /s/ Eric S. Lander, Ph.D.               Director                                       April 28, 2000
 -------------------------------------
   Eric S. Lander, Ph.D.

   /s/ Christopher K. Mirabelli, Ph.D.     Director                                       April 28, 2000
 -------------------------------------
   Christopher K. Mirabelli, Ph.D.

   /s/ Steven C. Wheelwright, Ph.D.        Director                                       April 28, 2000
 -------------------------------------
   Steven C. Wheelwright, Ph.D.
-7-
EXHIBIT INDEX
Exhibit
Number             Description
----------         ------------------------------------------------------
4.1                2000 Stock Incentive Plan
5.1                Opinion of Hale and Dorr LLP
23.1               Consent of Hale and Dorr LLP (included in Exhibit 5.1)
23.2               Consent of Ernst & Young LLP
23.3               Consent of PricewaterhouseCoopers LLP
23.4               Consent of Arthur Anderson LLP
24.1               Power of Attorney (included on the signature page to this Registration Statement)
-8-