Contacts:

Sharon Tetlow diaDexus 408-330-5003 stetlow@diadexus.com

diaDexus, Inc. files for initial public offering

Santa Clara, CA - November 20, 2000 - diaDexus, Inc. (www.diadexus.com) today filed a registration statement with the Securities and Exchange Commission for an initial public offering of its common stock. All of the shares to be offered will be sold by and for the account of diaDexus.

The managing underwriters of the offering are Lehman Brothers Inc., CIBC World Markets Corp., Prudential Vector Healthcare Group, a unit of Prudential Securities Incorporated and Fidelity Capital Markets. Copies of the preliminary prospectus, when available, may be obtained from Lehman Brothers c/o Automatic Data Processing, Inc., Prospectus Fulfillment, 55 Mercedes Way, Edgewood, New York 11717, (631) 254-7106 phone, (631) 254-7268 fax, e-mail: nwright@bis.adp.com.

diaDexus is a post-genomics company focused on translating raw genomics data into novel diagnostic and therapeutic products. diaDexus has utilized genomics and bioinformatics to identify thousands of disease-associated molecular targets. Currently diaDexus has two diagnostic product candidates in late-stage preclinical development.

A registration statement relating to these securities has been filed with the Securities and Exchange Commission, but has not yet become effective. These securities may not be sold, nor may offers to buy be accepted, prior to the time the registration statement becomes effective. This announcement shall not constitute an offer to sell or the solicitation of an offer to buy, nor shall there be any sales of these securities in any state or other jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or other jurisdiction. The offering will be made only by prospectus.