South San Francisco, California
January 17, 2002

Exelixis, Inc. (Nasdaq: EXEL) has delivered additional novel targets and assays to its partner Bayer in the companies' ongoing crop protection collaboration, Genoptera LLC. The delivery of these targets and assays triggers undisclosed milestone payments to Exelixis.

Genoptera LLC is an Exelixis-Bayer joint venture with the aim of identifying novel targets and providing assays for the discovery of new crop protection substances, in particular the discovery of novel insecticides and nematicides. The 2000 joint venture included a $20 million up-front payment and performance-based milestone and royalty payments to Exelixis as well as $80 million in research funding over the course of the eight-year joint venture.

"Since its establishment nearly two years ago, the Genoptera joint venture has resulted in the discovery of a substantial number of highly validated and novel targets and assays for our partner, Bayer," said George A. Scangos, Ph.D., president and chief executive officer of Exelixis. "I am confident that as our collaboration progresses, we will continue to deliver unique assays that may lead to the development of more effective, environmentally safe crop protection agents."

Exelixis, Inc. is a leading genomics-based drug discovery company focused on product development through its expertise in comparative genomics and model system genetics. These technologies provide a rapid, efficient and cost effective way to move from DNA sequence data to knowledge about the function of genes and the proteins they encode. The company's technology is broadly applicable to all life sciences industries including pharmaceutical, diagnostic, agricultural biotechnology and animal health. Exelixis has partnerships with Aventis CropScience, Bayer, Bristol-Myers Squibb, Elan Pharmaceuticals, Pharmacia, Protein Design Labs, Schering-Plough Research Institute, Scios Inc., Dow AgroSciences and Cytokinetics, Inc. and is building its internal development program in the area of oncology.

Exelixis and the Exelixis logo are registered U.S. trademarks.