<PAGE>
           As filed with the Securities and Exchange Commission on June 25, 2002

                                                       Registration No. 333-____


                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      under
                           THE SECURITIES ACT OF 1933

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


<TABLE>
<S>                                           <C>
                Delaware                        13-3159796
      (State or other jurisdiction            (I.R.S. Employer
          of incorporation or                 Identification No.)
              organization)


    58 South Service Road, Suite 110
             Melville, NY                           11747
(Address of principal executive offices)          (Zip Code)
</TABLE>


                              EMPLOYEE STOCK BONUS;
                            OSI PHARMACEUTICALS, INC.
                         NON-QUALIFIED STOCK OPTION PLAN
                             FOR FORMER EMPLOYEES OF
                             GILEAD SCIENCES, INC.;
                                       AND
                            OSI PHARMACEUTICALS, INC.
                               2001 INCENTIVE AND
                                  NON-QUALIFIED
                                STOCK OPTION PLAN
                            (Full title of the plan)

                             ROBERT L. VAN NOSTRAND
                   VICE PRESIDENT AND CHIEF FINANCIAL OFFICER
                            OSI PHARMACEUTICALS, INC.
                        58 SOUTH SERVICE ROAD, SUITE 110
                            MELVILLE, NEW YORK 11747
                                 (631) 962-2000
            (Name, address, including zip code, and telephone number,
                   including area code, of agent for service)

                                    Copy to:

                         SPENCER W. FRANCK, JR., ESQUIRE
                                 SAUL EWING LLP
                       1200 LIBERTY RIDGE DRIVE, SUITE 200
                            WAYNE, PENNSYLVANIA 19087
                                 (610) 251-5082

               See next page for calculation of registration fee.
<PAGE>
                         CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
                                      Proposed          Proposed
   Title of          Amount to        Maximum           Maximum
 Securities to          be            Offering         Aggregate        Amount of Registration
 be Registered      Registered       Price Per       Offering Price             Fee (2)
                        (1)            Share
<S>                 <C>              <C>           <C>                  <C>
Common Stock,
Par Value $.01
Per Share            4,760,249         $23.00       $109,485,727                $10,072.69
</TABLE>

(1)  Represents 750,249 shares issuable upon exercise of options granted under
     the Non-Qualified Stock Option Plan for Former Employees of Gilead
     Sciences, Inc.; 4,000,000 shares issuable upon exercise of options granted
     under the 2001 Incentive and Non-Qualified Stock Option Plan and 10,000
     shares issuable as a stock bonus pursuant to an employment letter with an
     executive of OSI Pharmaceuticals, Inc.

(2)  The registration fee has been computed in accordance with paragraphs (c)
     and (h) of Rule 457, based upon, in the case of options previously granted,
     the stated exercise price of such options, and, in the case of options
     still available for grant, the average of the reported high and low sale
     prices of shares of the Registrant's common stock on June 21, 2002.
<PAGE>
                                     PART I

              INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

Item 1. Plan Information.(1)

Item 2. Registrant Information and Employee Plan Annual Information.(1)

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3. Incorporation of Documents by Reference.

            The documents listed in clauses (a), (b) and (c) below are
incorporated herein by this reference thereto, and all documents subsequently
filed by the Registrant pursuant to Sections 13(a), 13(c), 14 and 15(d) of the
Securities Exchange Act of 1934, prior to the filing of a post-effective
amendment which indicates that all securities offered have been sold or which
deregisters all securities then remaining unsold, shall be deemed to be
incorporated by this reference in this registration statement and to be a part
hereof from the date of filing of such documents:

                  (a)   The Registrant's Annual Report on Form 10-K for the
                        fiscal year ended September 30, 2001.

                  (b)   The Registrant's Quarterly Reports on Form 10-Q for the
                        quarters ended December 31, 2001 and March 31, 2002, and
                        the Registrant's Current Reports on Form 8-K, dated
                        December 11, 2001, January 7, 2002, January 25, 2002,
                        January 29, 2002, and Form 8-K/A, dated March 6, 2002.

                  (c)   The description of the Registrant's common stock
                        contained in the registration statement filed by the
                        Registrant to register such securities under Section 12
                        of the Securities Exchange Act of 1934, including any
                        amendment or report filed for the purpose of updating
                        such description.

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 145 of the General Corporation Law of Delaware empowers a
corporation to indemnify any person who was or is a party or is threatened to be
made a party to any threatened, pending or completed action, suit or

--------

(1)  The information called for by Part I of this registration statement on Form
     S-8 is currently included in the Summary of the Employee Stock Bonus (the
     "Bonus"), the Summary of the Non-Qualified Stock Option Plan for Former
     Employees of Gilead Sciences, Inc. and the Summary of the 2001 Incentive
     and Non-Qualified Stock Option Plan (the "Plans") and will be delivered to
     eligible persons under the Bonus and the Plans as specified by Rule
     428(b)(1) of the Securities Act of 1933, as amended. Pursuant to the Note
     to Part I of Form S-8, this information is not being filed with or included
     in this Form S-8.
<PAGE>
proceeding, whether civil, criminal, administrative or investigative, by reason
of the fact that he or she is or was a director, officer, employee or agent of
the corporation or another enterprise if serving such enterprise at the request
of the corporation. Depending on the character of the proceeding, a corporation
may indemnify against expenses (including attorney's fees), judgments, fines and
amounts paid in settlement actually and reasonably incurred in connection with
such action, suit or proceeding if the person indemnified acted in good faith
and in a manner he or she reasonably believed to be in or not opposed to the
best interests of the corporation, and, with respect to any criminal action or
proceeding, had no reasonable cause to believe his or her conduct was unlawful.
In the case of an action by or in the right of the corporation, no
indemnification may be made in respect to any claim, issue or matter as to which
such person shall have been adjudged to be liable to the corporation unless and
only to the extent that the Court of Chancery or the court in which such action
or suit was brought shall determine that despite the adjudication of liability,
but in view of all the circumstances of the case, such person is fairly and
reasonably entitled to indemnity for such expenses that the court shall deem
proper. Section 145 further provides that to the extent a director or officer of
a corporation has been successful in the defense of any action, suit or
proceeding referred to above, or in defense of any claim, issue or matter
therein, he or she shall be indemnified against expenses (including attorney's
fees) actually and reasonably incurred by him or her in connection therewith.

            The Registrant's Certificate of Incorporation provides that the
Registrant shall, to the fullest extent authorized by the General Corporation
Law of Delaware, indemnify any person, or the legal representative of any
person, who is or was a director, officer, employee or agent of the Registrant
or another enterprise if said person served such enterprise at the request of
the Registrant. The Certificate of Incorporation also provides that any
amendment to the General Corporation Law of Delaware shall only be applicable to
the extent any such amendment permits the Registrant to provide broader
indemnification rights than said law permitted the Registrant to provide prior
to such amendment. The Certificate of Incorporation further provides that in the
case of an action, suit or proceeding initiated by the indemnified person, the
Registrant shall indemnify the person only if such action, suit or proceeding
was authorized by the Registrant's Board of Directors. The Certificate of
Incorporation also contains a provision eliminating the liability of directors
of the Registrant to itself or its stockholders for monetary damages for breach
of fiduciary duty except under certain specified circumstances. The Certificate
of Incorporation also permits the Registrant to maintain insurance to protect
itself and any director, officer, employee or agent against any liability with
respect to which the Registrant would have the power to indemnify such persons
under the General Corporation Law of Delaware. The Registrant maintains an
insurance policy insuring its directors and officers against certain
liabilities.

Item 7. Exemption from Registration Claimed.

            Not applicable.


Item 8. Exhibits.

            The following is a list of exhibits filed as part of the
registration statement:

             4.1  Non-Qualified Stock Option Plan for Former Employees of Gilead
                  Sciences, Inc.

             4.2  2001 Incentive and Non-Qualified Stock Option Plan.

             5    Opinion of Saul Ewing LLP.

            23.1  Consent of KPMG LLP.

            23.2  Consent of Ernst & Young, LLP, independent auditors.
<PAGE>
            23.3  Consent of Saul Ewing LLP (contained in Exhibit No. 5).

            24    Power of Attorney (included on signature page of the
                  registration statement).

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, 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.

                                    (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 (1)(i) and (1)(ii) above 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 or section 15(d) of the Securities Exchange Act of 1934
                  that are incorporated by reference in the 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
<PAGE>
      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 liability (other than
      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.
<PAGE>
                                   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, thereunder duly
authorized, in the City of Melville, State of New York, on June 25, 2002.


                                          OSI PHARMACEUTICALS, INC.


                                          By: /s/ Colin Goddard, Ph.D.
                                              --------------------------------
                                              Colin Goddard, Ph.D.
                                              Chairman of the Board and
                                              Chief Executive Officer


                                POWER OF ATTORNEY

            KNOW ALL MEN BY THESE PRESENTS, that each person whose signature
appears below hereby makes, constitutes and appoints Colin Goddard, Ph.D. and
Robert L. Van Nostrand and each of them, with full power to act without the
other, his true and lawful attorneys-in-fact and agents with full power of
substitution and resubstitution, for him and in his name, place and stead, in
any and all capacities to sign any and all amendments to this registration
statement on Form S-8, including post-effective amendments, 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
connection therewith, as fully to all intents and purposes as he might or could
do in person, hereby ratifying and confirming all that said attorneys-in-fact
and agents or any of them, or any 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.


<TABLE>
<CAPTION>
        Signature                                Title                     Date
<S>                                  <C>                               <C>
/s/ Colin Goddard, Ph.D.               Chairman of the Board and       June 25, 2002
---------------------------------       Chief Executive Officer
Colin Goddard, Ph.D.                          and Director


/s/ Robert L. Van Nostrand             Vice President and Chief        June 25, 2002
---------------------------------          Financial Officer
Robert L. Van Nostrand               (principal financial officer)

/s/ G. Morgan Browne                           Director                June 25, 2002
---------------------------------
G. Morgan Browne

/s/ John H. French, II                         Director                June 25, 2002
---------------------------------
John H. French, II
</TABLE>
<PAGE>
<TABLE>
<S>                                  <C>                               <C>
/s/ Edwin A. Gee, Ph.D.                        Director                June 25, 2002
---------------------------------
Edwin A. Gee, Ph.D.

/s/ Daryl K. Granner, M.D.                     Director                June 25, 2002
---------------------------------
Daryl K. Granner, M.D.

/s/ Walter M. Lovenberg, Ph.D.                 Director                June 25, 2002
---------------------------------
Walter M. Lovenberg, Ph.D.

/s/ Viren Mehta                                Director                June 25, 2002
---------------------------------
Viren Mehta

/s/ Sir Mark Richmond, Ph.D.                   Director                June 25, 2002
---------------------------------
Sir Mark Richmond, Ph.D.


/s/ John P. White, Esquire                     Director                June 25, 2002
---------------------------------
John P. White, Esquire
</TABLE>
<PAGE>
                                  EXHIBIT INDEX


<TABLE>
<CAPTION>
EXHIBIT NO.                          EXHIBIT
-----------                          -------

<S>                  <C>
 4.1                 Non-Qualified Stock Option Plan for Former Employees of Gilead
                     Sciences, Inc.

 4.2                 2001 Incentive and Non-Qualified Stock Option Plan.

 5                   Opinion of Saul Ewing LLP.

23.1                 Consent of KPMG LLP.

23.2                 Consent of Ernst & Young, LLP, independent
                     auditors.
23.3
                     Consent of Saul Ewing LLP (contained in Exhibit
                     No. 5).
24
                     Power of Attorney (included on signature page of the
                     registration statement).
</TABLE>
[{"type": "S-8", "sequence": "1", "filename": "y61737sv8.txt", "description": "OSI PHARMACEUTICALS, INC", "secsgml_size_bytes": 20804}]
{"company-data": {"conformed-name": "OSI PHARMACEUTICALS INC", "cik": "0000729922", "assigned-sic": "2835", "irs-number": "133159796", "state-of-incorporation": "DE", "fiscal-year-end": "0930"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-91118", "film-number": "02686412"}, "business-address": {"street1": "106 CHARLES LINDBERGH BLVD", "city": "UNIONDALE", "state": "NY", "zip": "11553", "phone": "5162220023"}, "mail-address": {"street1": "106 CHARLES LINDBERGH BLVD", "city": "UNIONDALE", "state": "NY", "zip": "11553-3649"}, "former-company": {"former-conformed-name": "ONCOGENE SCIENCE INC", "date-changed": "19920703"}}
As filed with the Securities and Exchange Commission on June 25, 2002

                                                       Registration No. 333-____

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      under
                           THE SECURITIES ACT OF 1933

                            OSI PHARMACEUTICALS, INC.
             (Exact name of registrant as specified in its charter)
Delaware                        13-3159796
      (State or other jurisdiction            (I.R.S. Employer
          of incorporation or                 Identification No.)
              organization)

    58 South Service Road, Suite 110
             Melville, NY                           11747
(Address of principal executive offices)          (Zip Code)
EMPLOYEE STOCK BONUS;
                            OSI PHARMACEUTICALS, INC.
                         NON-QUALIFIED STOCK OPTION PLAN
                             FOR FORMER EMPLOYEES OF
                             GILEAD SCIENCES, INC.;
                                       AND
                            OSI PHARMACEUTICALS, INC.
                               2001 INCENTIVE AND
                                  NON-QUALIFIED
                                STOCK OPTION PLAN
                            (Full title of the plan)

                             ROBERT L. VAN NOSTRAND
                   VICE PRESIDENT AND CHIEF FINANCIAL OFFICER
                            OSI PHARMACEUTICALS, INC.
                        58 SOUTH SERVICE ROAD, SUITE 110
                            MELVILLE, NEW YORK 11747
                                 (631) 962-2000
            (Name, address, including zip code, and telephone number,
                   including area code, of agent for service)

                                    Copy to:

                         SPENCER W. FRANCK, JR., ESQUIRE
                                 SAUL EWING LLP
                       1200 LIBERTY RIDGE DRIVE, SUITE 200
                            WAYNE, PENNSYLVANIA 19087
                                 (610) 251-5082

               See next page for calculation of registration fee.
CALCULATION OF REGISTRATION FEE
Proposed          Proposed
   Title of          Amount to        Maximum           Maximum
 Securities to          be            Offering         Aggregate        Amount of Registration
 be Registered      Registered       Price Per       Offering Price             Fee (2)
                        (1)            Share
Common Stock,
Par Value $.01
Per Share            4,760,249         $23.00       $109,485,727                $10,072.69
(1)  Represents 750,249 shares issuable upon exercise of options granted under
     the Non-Qualified Stock Option Plan for Former Employees of Gilead
     Sciences, Inc.; 4,000,000 shares issuable upon exercise of options granted
     under the 2001 Incentive and Non-Qualified Stock Option Plan and 10,000
     shares issuable as a stock bonus pursuant to an employment letter with an
     executive of OSI Pharmaceuticals, Inc.

(2)  The registration fee has been computed in accordance with paragraphs (c)
     and (h) of Rule 457, based upon, in the case of options previously granted,
     the stated exercise price of such options, and, in the case of options
     still available for grant, the average of the reported high and low sale
     prices of shares of the Registrant's common stock on June 21, 2002.
PART I

              INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

Item 1. Plan Information.(1)

Item 2. Registrant Information and Employee Plan Annual Information.(1)

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3. Incorporation of Documents by Reference.

            The documents listed in clauses (a), (b) and (c) below are
incorporated herein by this reference thereto, and all documents subsequently
filed by the Registrant pursuant to Sections 13(a), 13(c), 14 and 15(d) of the
Securities Exchange Act of 1934, prior to the filing of a post-effective
amendment which indicates that all securities offered have been sold or which
deregisters all securities then remaining unsold, shall be deemed to be
incorporated by this reference in this registration statement and to be a part
hereof from the date of filing of such documents:

                  (a)   The Registrant's Annual Report on Form 10-K for the
                        fiscal year ended September 30, 2001.

                  (b)   The Registrant's Quarterly Reports on Form 10-Q for the
                        quarters ended December 31, 2001 and March 31, 2002, and
                        the Registrant's Current Reports on Form 8-K, dated
                        December 11, 2001, January 7, 2002, January 25, 2002,
                        January 29, 2002, and Form 8-K/A, dated March 6, 2002.

                  (c)   The description of the Registrant's common stock
                        contained in the registration statement filed by the
                        Registrant to register such securities under Section 12
                        of the Securities Exchange Act of 1934, including any
                        amendment or report filed for the purpose of updating
                        such description.

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 145 of the General Corporation Law of Delaware empowers a
corporation to indemnify any person who was or is a party or is threatened to be
made a party to any threatened, pending or completed action, suit or

--------

(1)  The information called for by Part I of this registration statement on Form
     S-8 is currently included in the Summary of the Employee Stock Bonus (the
     "Bonus"), the Summary of the Non-Qualified Stock Option Plan for Former
     Employees of Gilead Sciences, Inc. and the Summary of the 2001 Incentive
     and Non-Qualified Stock Option Plan (the "Plans") and will be delivered to
     eligible persons under the Bonus and the Plans as specified by Rule
     428(b)(1) of the Securities Act of 1933, as amended. Pursuant to the Note
     to Part I of Form S-8, this information is not being filed with or included
     in this Form S-8.
proceeding, whether civil, criminal, administrative or investigative, by reason
of the fact that he or she is or was a director, officer, employee or agent of
the corporation or another enterprise if serving such enterprise at the request
of the corporation. Depending on the character of the proceeding, a corporation
may indemnify against expenses (including attorney's fees), judgments, fines and
amounts paid in settlement actually and reasonably incurred in connection with
such action, suit or proceeding if the person indemnified acted in good faith
and in a manner he or she reasonably believed to be in or not opposed to the
best interests of the corporation, and, with respect to any criminal action or
proceeding, had no reasonable cause to believe his or her conduct was unlawful.
In the case of an action by or in the right of the corporation, no
indemnification may be made in respect to any claim, issue or matter as to which
such person shall have been adjudged to be liable to the corporation unless and
only to the extent that the Court of Chancery or the court in which such action
or suit was brought shall determine that despite the adjudication of liability,
but in view of all the circumstances of the case, such person is fairly and
reasonably entitled to indemnity for such expenses that the court shall deem
proper. Section 145 further provides that to the extent a director or officer of
a corporation has been successful in the defense of any action, suit or
proceeding referred to above, or in defense of any claim, issue or matter
therein, he or she shall be indemnified against expenses (including attorney's
fees) actually and reasonably incurred by him or her in connection therewith.

            The Registrant's Certificate of Incorporation provides that the
Registrant shall, to the fullest extent authorized by the General Corporation
Law of Delaware, indemnify any person, or the legal representative of any
person, who is or was a director, officer, employee or agent of the Registrant
or another enterprise if said person served such enterprise at the request of
the Registrant. The Certificate of Incorporation also provides that any
amendment to the General Corporation Law of Delaware shall only be applicable to
the extent any such amendment permits the Registrant to provide broader
indemnification rights than said law permitted the Registrant to provide prior
to such amendment. The Certificate of Incorporation further provides that in the
case of an action, suit or proceeding initiated by the indemnified person, the
Registrant shall indemnify the person only if such action, suit or proceeding
was authorized by the Registrant's Board of Directors. The Certificate of
Incorporation also contains a provision eliminating the liability of directors
of the Registrant to itself or its stockholders for monetary damages for breach
of fiduciary duty except under certain specified circumstances. The Certificate
of Incorporation also permits the Registrant to maintain insurance to protect
itself and any director, officer, employee or agent against any liability with
respect to which the Registrant would have the power to indemnify such persons
under the General Corporation Law of Delaware. The Registrant maintains an
insurance policy insuring its directors and officers against certain
liabilities.

Item 7. Exemption from Registration Claimed.

            Not applicable.

Item 8. Exhibits.

            The following is a list of exhibits filed as part of the
registration statement:

             4.1  Non-Qualified Stock Option Plan for Former Employees of Gilead
                  Sciences, Inc.

             4.2  2001 Incentive and Non-Qualified Stock Option Plan.

             5    Opinion of Saul Ewing LLP.

            23.1  Consent of KPMG LLP.

            23.2  Consent of Ernst & Young, LLP, independent auditors.
23.3  Consent of Saul Ewing LLP (contained in Exhibit No. 5).

            24    Power of Attorney (included on signature page of the
                  registration statement).

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, 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.

                                    (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 (1)(i) and (1)(ii) above 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 or section 15(d) of the Securities Exchange Act of 1934
                  that are incorporated by reference in the 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 liability (other than
      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.
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, thereunder duly
authorized, in the City of Melville, State of New York, on June 25, 2002.

                                          OSI PHARMACEUTICALS, INC.

                                          By: /s/ Colin Goddard, Ph.D.
                                              --------------------------------
                                              Colin Goddard, Ph.D.
                                              Chairman of the Board and
                                              Chief Executive Officer

                                POWER OF ATTORNEY

            KNOW ALL MEN BY THESE PRESENTS, that each person whose signature
appears below hereby makes, constitutes and appoints Colin Goddard, Ph.D. and
Robert L. Van Nostrand and each of them, with full power to act without the
other, his true and lawful attorneys-in-fact and agents with full power of
substitution and resubstitution, for him and in his name, place and stead, in
any and all capacities to sign any and all amendments to this registration
statement on Form S-8, including post-effective amendments, 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
connection therewith, as fully to all intents and purposes as he might or could
do in person, hereby ratifying and confirming all that said attorneys-in-fact
and agents or any of them, or any 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/ Colin Goddard, Ph.D.               Chairman of the Board and       June 25, 2002
---------------------------------       Chief Executive Officer
Colin Goddard, Ph.D.                          and Director

/s/ Robert L. Van Nostrand             Vice President and Chief        June 25, 2002
---------------------------------          Financial Officer
Robert L. Van Nostrand               (principal financial officer)

/s/ G. Morgan Browne                           Director                June 25, 2002
---------------------------------
G. Morgan Browne

/s/ John H. French, II                         Director                June 25, 2002
---------------------------------
John H. French, II
/s/ Edwin A. Gee, Ph.D.                        Director                June 25, 2002
---------------------------------
Edwin A. Gee, Ph.D.

/s/ Daryl K. Granner, M.D.                     Director                June 25, 2002
---------------------------------
Daryl K. Granner, M.D.

/s/ Walter M. Lovenberg, Ph.D.                 Director                June 25, 2002
---------------------------------
Walter M. Lovenberg, Ph.D.

/s/ Viren Mehta                                Director                June 25, 2002
---------------------------------
Viren Mehta

/s/ Sir Mark Richmond, Ph.D.                   Director                June 25, 2002
---------------------------------
Sir Mark Richmond, Ph.D.

/s/ John P. White, Esquire                     Director                June 25, 2002
---------------------------------
John P. White, Esquire
EXHIBIT INDEX
EXHIBIT NO.                          EXHIBIT
-----------                          -------
4.1                 Non-Qualified Stock Option Plan for Former Employees of Gilead
                     Sciences, Inc.

 4.2                 2001 Incentive and Non-Qualified Stock Option Plan.

 5                   Opinion of Saul Ewing LLP.

23.1                 Consent of KPMG LLP.

23.2                 Consent of Ernst & Young, LLP, independent
                     auditors.
23.3
                     Consent of Saul Ewing LLP (contained in Exhibit
                     No. 5).
24
                     Power of Attorney (included on signature page of the
                     registration statement).