Exhibit 99.1

FOR IMMEDIATE RELEASE

Abgenix Announces Third Quarter 2005 Financial Results

FREMONT, Calif. - October 25, 2005 - Abgenix, Inc. (NASDAQ: ABGX) today announced financial results for the third quarter ended September 30, 2005.  The company reported a net loss of $36.8 million, or $0.41 per share, for the third quarter of 2005, compared to $42.4 million, or $0.48 per share, for the same period in 2004.

Net cash used in operating activities in the third quarter of 2005 was $21.8 million, compared to $36.5 million in the third quarter of 2004.  During the quarter, the company repurchased approximately $13.8 million of its outstanding convertible notes due in 2007, and ended the third quarter of 2005 with $343.6 million in cash, cash equivalents and marketable securities. 

“We continue to execute on our goals for 2005, including progress with our partner, Amgen, towards the initiation of our regulatory filing to the FDA for panitumumab before year-end 2005,” said Bill Ringo, president and chief executive officer of Abgenix.  “Our third quarter performance reflects expense reductions realized from our recently announced restructuring and facility consolidation, efforts to expand our product portfolio, and investment in the development and potential commercialization of panitumumab.”

Revenues for the third quarter of 2005 were $4.7 million compared to $3.1 million for the same period in 2004.  Revenues for the third quarter of 2005 consisted primarily of contract revenues from technology licensing agreements and included licensing revenues and an IND-related milestone from our partner Agensys.  For the third quarter of 2004, revenues included a milestone payment from Amgen for advancement of denosumab (AMG-162), a XenoMouse^®-derived antibody, into pivotal clinical trials for bone loss.  The company’s contract revenues generally vary from period to period based on the progress of research and development efforts by the company’s collaborators and licensees.

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