EXHIBIT 23.1

            CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

The Board of Directors
OSI Pharmaceuticals, Inc.:

     We consent to the incorporation by reference of our report dated November
29, 2004, with respect to the consolidated balance sheets of OSI
Pharmaceuticals, Inc. and subsidiaries as of September 30, 2004 and 2003, and
the related consolidated statements of operations, stockholders' equity, and
cash flows for each of the years in the three-year period ended September 30,
2004, and to the reference to our firm under the heading "Experts" in this
Registration Statement on Form S-3 and related prospectus.

     As discussed in Note 1 (b) to the consolidated financial statements, the
Company adopted EITF 00-21 "Revenue Arrangements with Multiple Deliverables" in
2004.

     As discussed in notes 1(j) and 8 to the consolidated financial statements,
the Company fully adopted the provisions of Statement of Financial Accounting
Standards No. 142, "Goodwill and Other Intangible Assets" in 2003.

     As discussed in notes 10 to the consolidated financial statements, the
Company early adopted Statement of Financial Accounting Standards No. 145
"Rescission of FASB Statements No. 4, 44 and 64, Amendment of FASB Statement No.
13, and Technical Corrections" relating to the classification of the effect of
early debt extinguishments in 2002.

                                          /s/ KPMG LLP

Melville, New York
April 21, 2005