Maxygen Fourth Quarter and Year End 2008 Financial Results Conference Call Notice

Maxygen, Inc. (Nasdaq:MAXY), a biotechnology company focused on the development of improved protein drugs, will host a conference call to discuss the company’s fourth quarter and year end 2008 financial results at 4:30 p.m. ET (1:30 p.m. PT) on Tuesday, February 10, 2009. Russell Howard, Maxygen’s chief executive officer, will host the call. A press release announcing Maxygen’s fourth quarter and year end 2008 financial results will be issued that same day at approximately 4:00 p.m. ET (1:00 p.m. PT).

Participants in the U.S. can access the call by dialing 866.221.6685 and using the passcode 93293610. International participants can dial 617.896.9885 and use the same passcode. A live webcast of the conference call will be available on the Maxygen web site at www.maxygen.com/webcasts.

Telephone and webcast replays of the conference call will be available until March 10, 2009. To access the telephone replay, dial 888.286.8010 (U.S.) or 617.801.6888 (international) and use the passcode 40855606. To access the webcast archive, go to www.maxygen.com/webcasts.

About Maxygen

Maxygen is a biopharmaceutical company focused on developing improved versions of protein drugs. The company’s portfolio includes MAXY-G34, designed to be an improved long-acting G-CSF for the treatment of neutropenia. Maxygen also has a MAXY-4 program, partnered with Astellas Pharma, Inc., under which the company and Astellas are exploring new CTLA4-Ig product candidates for the treatment of a broad array of autoimmune disorders and transplantation rejection. Maxygen uses its proprietary DNA shuffling technology and extensive protein modification expertise to pursue the creation of biosuperior proteins. www.maxygen.com