OSI Pharmaceuticals to Present at The Thomas Weisel Partners Healthcare Conference on Wednesday, September 9, 2009

OSI Pharmaceuticals, Inc. (NASDAQ:OSIP) announced today that OSI Management will present at the Thomas Weisel Partners Healthcare Conference in Boston, MA on Wednesday, September 9, 2009 at 1:30pm (Eastern Time) and 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 September 23, 2009.

About OSI Pharmaceuticals

OSI Pharmaceuticals is committed to "shaping medicine and changing lives" by discovering, developing and commercializing high-quality, novel and differentiated targeted medicines designed to extend life and improve the quality of life for patients with cancer and diabetes/obesity. For additional information about OSI, please visit http://www.osip.com.

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, OSI's and its collaborators' abilities to effectively market and sell Tarceva and to expand the approved indications for Tarceva, OSI’s ability to protect its intellectual property rights, safety concerns regarding Tarceva, competition to Tarceva and OSI’s drug candidates from other biotechnology and pharmaceutical companies, the completion of clinical trials, the effects of FDA and other governmental regulation, including pricing controls, OSI's ability to successfully develop and commercialize drug candidates, and other factors described in OSI Pharmaceuticals' filings with the Securities and Exchange Commission.