UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549


                                    FORM 8-K


                CURRENT REPORT PURSUANT TO SECTION 13 OR 15(d) OF
                       THE SECURITIES EXCHANGE ACT OF 1934

                                   May 2, 2005
                ------------------------------------------------
                Date of Report (Date of earliest event reported)

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


          DELAWARE                        0-15190                13-3159796
- -------------------------------         -----------          -------------------
(State or other jurisdiction of         (Commission           (I.R.S. Employer
        incorporation)                  File Number)         Identification No.)


                              58 SOUTH SERVICE ROAD
                               MELVILLE, NY 11747
                    ----------------------------------------
                    (Address of principal executive offices)

                                 (631) 962-2000
              ----------------------------------------------------
              (Registrant's telephone number, including area code)

                                       N/A
                         -------------------------------
                         (Former name or former address,
                         if changed since last report.)

Check the appropriate box below if the Form 8-K filing is intended to
simultaneously satisfy the filing obligation of the registrant under any of the
following provisions:

[ ]  Written communications pursuant to Rule 425 under the Securities Act (17
     CFR 230.425)

[ ]  Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17
     CFR 240.14a-12)

[ ]  Pre-commencement communications pursuant to Rule 14d-2(b) under the
     Exchange Act (17 CFR 240.14d-2(b))

[ ]  Pre-commencement communications pursuant to Rule 13e-4(c) under the
     Exchange Act (17 CFR 240.13e-4(c))





ITEM 2.02 RESULTS OF OPERATIONS AND FINANCIAL CONDITION

         On May 2, 2005, OSI Pharmaceuticals, Inc. (the "Company") issued a
press release regarding its financial results for the quarter ended March 31,
2005. The Company's press release is attached as Exhibit 99.1 to this Current
Report on Form 8-K and is incorporated by reference herein.

         The information under this item and Exhibit 99.1 attached hereto is
being "furnished" and shall not be deemed "filed" for purposes of Section 18 of
the Securities Exchange Act of 1934 (the "Exchange Act") or otherwise subject to
the liabilities of that section, nor shall it be deemed incorporated by
reference in any filing under the Securities Act of 1933 (the "Securities Act")
or the Exchange Act, except if the Company specifically states that the
information and the Exhibit is to be considered "filed" under the Exchange Act
or incorporates it by reference into a filing under the Securities Act or the
Exchange Act.

ITEM 8.01 OTHER EVENTS

         On May 2, 2005, OSI issued a press release announcing the filing of a
supplemental New Drug Application with the U.S. Food and Drug Administration for
the use of Tarceva(TM) (erlotinib) plus gemcitabine chemotherapy for the
treatment of advanced pancreatic cancer in patients who have not received any
prior treatment. The press release is attached hereto as Exhibit 99.2 to this
Form 8-K and is incorporated herein by reference.

         On May 3, 2005, the Company held a webcast conference call regarding
its financial results for the quarter ended March 31, 2005 as well as an update
on the Company's business. A textual representation of certain portions of the
conference call is attached as Exhibit 99.3 to this Current Report on Form 8-K
and is incorporated by reference herein.

ITEM 9.01 EXHIBITS


<Table>
<Caption>
     EXHIBIT NO.                              DESCRIPTION
- ----------------------- --------------------------------------------------------
                     
         99.1           Press release, dated May 2, 2005.

         99.2           Press release, dated May 2, 2005.

         99.3           Textual representation of certain portions of the
                        webcast conference call held on May 3, 2005
</Table>





                                    SIGNATURE

         Pursuant to the requirements of the Securities Exchange Act of 1934,
the registrant has duly caused this report to be signed on its behalf by the
undersigned hereunto duly authorized.


Date:    May 6, 2005                   OSI PHARMACEUTICALS, INC.


                                       By: /s/ Robert L. Van Nostrand
                                           -------------------------------------
                                           Robert L. Van Nostrand
                                           Vice President and Chief Financial
                                           Officer (Principal Financial Officer)





                                  EXHIBIT INDEX


<Table>
<Caption>
     EXHIBIT NO.                            DESCRIPTION
- ----------------------- --------------------------------------------------------
                     
         99.1           Press release, dated May 2, 2005.

         99.2           Press release, dated May 2, 2005.

         99.3           Textual representation of certain portions of the
                        webcast conference call held on May 3, 2005
</Table>