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

                                 March 22, 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 8.01 OTHER EVENTS

      On March 22, 2005, OSI Pharmaceuticals, Inc. (the "Company") issued a
press release relating to the approval of Tarceva(TM) by the Swiss health
authority, Swissmedic, for patients with advanced non-small cell lung cancer.
The Company's press release is attached as Exhibit 99.1 to this Current Report
on Form 8-K and is incorporated herein by reference.

ITEM 9.01 EXHIBITS



 EXHIBIT NO.                      DESCRIPTION
 -----------                      -----------
                  
    99.1             Press release, dated March 22, 2005.


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                                    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: March 29, 2005                             OSI PHARMACEUTICALS, INC.

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

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                                 EXHIBIT INDEX



EXHIBIT NO.                       DESCRIPTION
- -----------                       -----------
                  
    99.1             Press release, dated March 22, 2005.


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