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                                FORM 10-K/A NO.2
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
(Mark One)
/X/     Annual Report Pursuant to Section 13 or 15(d) of the Securities
        Exchange Act of 1934

For the fiscal year ended    September 30, 1997    or

/ /     Transition Report Pursuant to Section 13 or 15(d) of the Securities
        Exchange Act of 1934

For the transition period from          to

Commission file number               0-15190

                            OSI Pharmaceuticals, Inc.
             (Exact name of Registrant as specified in its charter)

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

106 Charles Lindbergh Blvd., Uniondale, N.Y.                  11553
  (Address of principal executive offices)                  (Zip Code)

        Registrant's telephone number, including area code (516) 222-0023

           SECURITIES REGISTERED PURSUANT TO SECTION 12(B) OF THE ACT:

     Title of each class             Name of each exchange on which registered
            None                                       None

           SECURITIES REGISTERED PURSUANT TO SECTION 12(G) OF THE ACT:
                     Common Stock, par value $.01 per share
                                (Title of Class)

Indicate by check mark whether the Registrant (1) has filed all reports required
to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during
the preceding 12 months (or for such shorter period that the Registrant was
required to file such reports), and (2) has been subject to such filing 
requirements for the past 90 days.
Yes   /X/      No   / /

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405
of Regulation S-K is not contained herein, and will not be contained, to the
best of Registrant's knowledge, in definitive proxy or information statements
incorporated by reference in Part III of this Form 10-K or any amendment to this
Form 10-K. / /

As of November 28, 1997, the aggregate market value of the Registrant's voting
stock held by non-affiliates was $133,215,769. For purposes of this calculation,
shares of Common Stock held by directors, officers and stockholders whose
ownership exceeds five percent of the Common Stock outstanding at November 28,
1997 were excluded. Exclusion of shares held by any person should not be
construed to indicate that such person possesses the power, direct or indirect,
to direct or cause the direction of the management or policies of the
Registrant, or that such person is controlled by or under common control with
the Registrant.

As of November 28, 1997, there were 22,263,969 shares of the Registrant's $.01
par value common stock outstanding.

                       DOCUMENTS INCORPORATED BY REFERENCE

         Portions of the Registrant's definitive proxy statement for its 1998
annual meeting of stockholders are incorporated by reference into Part III.



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                                    SIGNATURE

         Pursuant to the requirements of Section 13 or 15(d) of the Securities
and Exchange Act of 1934, the Company has duly caused this report to be signed
on its behalf by the undersigned, thereunto duly authorized.

                                        OSI PHARMACEUTICALS, INC.


                                        By:      /s/ Robert L. Van Nostrand
                                                 --------------------------
                                                 Robert L. Van Nostrand
                                                 Chief Financial Officer


Date:  April 9, 1998


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                                INDEX TO EXHIBITS

Exhibits

  3.1         Certificate of Incorporation, as amended (1)

  3.2         Bylaws, as amended (1)

 10.1         1985 Stock Option Plan (filed as an exhibit to the Company's
              registration statement on Form S-1 (file no. 33-3148) and 
              incorporated herein by reference)

 10.2         1989 Incentive and Non-Qualified Stock Option Plan (filed as an 
              exhibit to the Company's registration statement on Form S-8 (file 
              no. 33-38443) and incorporated herein by reference)

 10.3         1993 Incentive and Non-Qualified Stock Option Plan, as amended 
              (filed as an exhibit to the Company's registration statement on 
              Form S-8 (file no. 33-64713) and incorporated herein by
              reference)

 10.4         Stock Purchase Plan for Non-Employee Directors (filed as an
              exhibit to the Company's registration statement on Form S-8 (file
              no. 333-06861) and incorporated herein by reference)

 10.5         1995 Employee Stock Purchase Plan (filed as an exhibit to the
              Company's registration statement on Form S-8 (file no. 333-06861)
              and incorporated herein by reference)

 10.6         1997 Incentive and Non-Qualified Stock Option Plan (filed as an 
              exhibit to the Company's registration statement on Form S-8 (file 
              no. 333-39509) and incorporated herein by reference)

 10.7+        Collaborative Research Agreement dated April 1, 1996 between the 
              Company and Pfizer Inc. (2)

 10.8+        License Agreement dated April 1, 1996 between the Company and 
              Pfizer Inc. (2)

 10.9+        Stockholders' Agreement dated April 23, 1996 among Anaderm 
              Research Corp., the Company, Pfizer Inc., New York University and
              certain individuals (2)

10.10+        Collaborative Research Agreement dated April 23,1996 amount the 
              Company, Pfizer Inc. and Anaderm Research Corp. (2)

10.11         Registration Rights Agreement dated April 11, 1996 among the 
              Company and the former stockholders of MYCOsearch, Inc. and their 
              designees (2)


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10.12         Form of Warrants issued by the Company to the former stockholders 
              of MYCOsearch, Inc. and their designees covering an aggregate of 
              100,000 shares of common stock (2)

10.13         Employment Agreement dated April 11, 1996 between the Company and
              Dr. Barry Katz (2)
             
10.14+        Collaborative Research Agreement dated as of December 31, 1991 
              between the Company and American Home Products Corporation (3)
             
10.15+        Amendatory Agreement dated as of December 31, 1993 between the 
              Company and American Home Products Corporation (3)
             
10.16**       Common Stock Purchase Warrant granted to Marion Merrell Dow, Inc.
              dated December 11, 1992
             
10.17         Collaborative Agreement dated as of April 19, 1995 between the 
              Company and Novartis Pharma AG (4)
             
10.18         Letter Agreement dated as of April 19, 1995 between the Company
              and Novartis Pharma AG (4)
             
10.19         Registration Rights Agreement dated as of April 19, 1995 between 
              the Company and Novartis Pharma AG (4)
             
10.20         Asset Purchase Agreement dated June 26, 1995 among the Company, 
              Calbiochem-Novabiochem International, Inc. and 
              Calbiochem-Novabiochem Corporation (5)
             
10.21         New Product License Right of First Refusal Agreement dated August 
              2, 1995 between the Company and Calbiochem-Novabiochem
              Corporation (5)
            
10.22         Employment Agreement dated as of February 9, 1990 between the 
              Company and Gary E. Frashier (6)

10.23         Form of Employment Agreement dated as of August 27, 1991, which 
              is substantially identical in all material respects to the
              Employment Agreement dated as of April 28, 1993 between the 
              Company and Colin Goddard, Ph.D. (6)

10.24+        Agreement dated September 27, 1996 between the Company and Becton,
              Dickinson and Company (6)

10.25+        Collaborative Research and License Agreement dated as of January 
              1, 1997 between the Company and Bayer Corporation (7)

10.26+        Collaborative Research, Development and Commercialization
              Agreement dated as of May 1, 1996 between the Company and BioChem
              Pharma (International) Inc. (7)


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10.27+        EPO Collaborative Research and License Agreement dated as of 
              January 1, 1997 between the Company and Hoechst Marion Roussel,
              Inc. (8)

10.28+        Collaborative Research, Development and License Agreement dated as
              of February 12, 1997 by and among the Company, Sankyo Company,
              Ltd., and MRC Collaborative Center (8)

10.29+        Collaborative Research, Development and Commercialization
              Agreement dated as of March 7, 1997
              between the Company and Sepracor, Inc. (8)

10.30+        License Agreement dated as of March 18, 1997 between the Company
              and The Dow Chemical Company (8)

10.31         Amended and Restated Collaborative Research and License Agreement
              effective as of April 1, 1997 by and among the Company, Hoechst
              Marion Roussel, Inc. and Hoechst Aktiengesellschaft (9)

10.32**+      Stock Subscription Agreement dated as of July 17, 1997 by and 
              between the Company and Helicon Therapeutics, Inc.

10.33*+       License and Services Agreement dated as of July 17, 1997 by and
              between the Company and Helicon Therapeutics, Inc.

10.34*+       Stockholders' Agreement dated as of July 17, 1997 by and among
              Helicon Therapeutics, Inc. and certain stockholders of Helicon 
              Therapeutics, Inc.

10.35*+       Convertible Preferred Stock Purchase Agreement dated as of July 
              17, 1997 by and among Helicon Therapeutics, Inc., the Company, 
              Hoffman-La Roche, Inc. and Cold Spring Harbor Laboratory.

10.36**+      Collaborative Research and License Agreement effective as of July 
              1, 1997 by and between Hoffman-La Roche, Inc. and Helicon
              Therapeutics, Inc.

21**          Subsidiaries of the Company

23**          Consent of KPMG Peat Marwick, LLP, independent public accountants

27**          Financial Data Schedule

99**          Additional Exhibits: Risk Factors

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*        Filed herewith.

**       Previously filed.


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+        Portions of this exhibit have been redacted and are subject to a
         confidential treatment request filed with the Secretary of the
         Securities and Exchange Commission pursuant to Rule 24b-2 under the
         Securities Exchange Act of 1934, as amended.

(1)      Filed as an exhibit to the Company's registration statement on Form S-3
         (file no. 333-937) and incorporated herein by reference.

(2)      Filed as an exhibit to the Company's quarterly report on Form 10-Q for
         the fiscal quarter ended March 31, 1996, as amended, and incorporated
         herein by reference.

(3)      Filed as an exhibit to the Company's quarterly report on Form 10-Q for
         the fiscal quarter ended December 31, 1995, as amended, and
         incorporated herein by reference.

(4)      Filed as an exhibit to the Company's annual report on Form 10-K for the
         fiscal year ended September 30, 1995, as amended, and incorporated
         herein by reference.

(5)      Filed as an exhibit to the Company's current report on Form 8-K dated
         August 2, 1995 and incorporated herein by reference.

(6)      Filed as an exhibit to the Company's annual report on Form 10-K for the
         fiscal year ended September 30, 1996 and incorporated herein by
         reference.

(7)      Filed as an exhibit to the Company's quarterly report on Form 10-Q for
         the fiscal quarter ended December 31, 1996 and incorporated herein by
         reference.

(8)      Filed as an exhibit to the Company's quarterly report on Form 10-Q for
         the fiscal quarter ended March 31, 1997 and incorporated herein by
         reference.

(9)      Filed as an exhibit to the Company's quarterly report on Form 10-Q for
         the fiscal quarter ended June 30, 1997 and incorporated herein by
         reference.


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