OSI Pharmaceuticals to Present at the Cowen and Company 29th Annual Healthcare Conference on Monday, March 16, 2009

OSI Pharmaceuticals, Inc. (NASDAQ: OSIP) announced today that Mr. Pierre Legault, Executive Vice President & Chief Financial Officer of OSI Pharmaceuticals, will present at the Cowen Healthcare Conference in Boston, MA on Monday, March 16, 2009 at 2:25p.m. (Eastern Time). Mr. Legault will provide an overview on the Company’s product portfolio and business developments.

The presentation will be webcast live and may be accessed by visiting OSI’s website at www.osip.com. A replay of the webcast will also be available on the Company’s website until March 30, 2009.

About OSI Pharmaceuticals

OSI Pharmaceuticals is committed to "shaping medicine and changing lives" by discovering, developing and commercializing high-quality and novel pharmaceutical products designed to extend life and/or improve the quality of life for patients with cancer and diabetes/obesity. The Company’s oncology programs are focused on developing molecular targeted therapies designed to change the paradigm of cancer care. OSI’s diabetes/obesity efforts are committed to the generation of novel, targeted therapies for the treatment of type 2 diabetes and obesity. OSI's flagship product, Tarceva® (erlotinib), is the first drug discovered and developed by OSI to obtain FDA approval and the only EGFR inhibitor to have demonstrated the ability to improve survival in both non-small cell lung cancer and pancreatic cancer patients in certain settings. OSI markets Tarceva through partnerships with Genentech, Inc. in the United States and with Roche throughout the rest of the world. For additional information about OSI, please visit .

This news release contains forward-looking statements. These statements are subject to known and unknown risks and uncertainties that may cause actual future experience and results to differ materially from the statements made. Factors that might cause such a difference include, among others, the completion of clinical trials, the FDA review process and other governmental regulation, OSI's and its collaborators' abilities to successfully develop and commercialize drug candidates, competition from other pharmaceutical companies, the ability to effectively market products, and other factors described in OSI Pharmaceuticals' filings with the Securities and Exchange Commission.