The Woodlands, Texas, February 26, 2007 – Lexicon Genetics Incorporated (Nasdaq: LEXG) announced today two promotions in the company’s senior management team.  Brian P. Zambrowicz, Ph.D. has been appointed executive vice president and chief scientific officer, from executive vice president of research, and Alan J. Main, Ph.D. has been promoted to executive vice president of pharmaceutical research, from senior vice president.

“Drs. Zambrowicz and Main are instrumental to the success of our 10_TO10 initiative, our program to bring 10 new drug candidates into clinical development through 2010,” said Arthur T. Sands, M.D., Ph.D., Lexicon’s president and chief executive officer.  “The drug candidates we already have in development under this program represent potential new medicines that we believe may address significant unmet medical needs.  In their new roles, Brian and Alan will have expanded responsibilities in directing preclinical development as well as fostering growth of Lexicon’s network of pharmaceutical and biotechnology alliances.”

Dr. Zambrowicz, who joined Lexicon in April 1996, was a key inventor of the company’s high-throughput gene trapping technology and was instrumental in establishing Lexicon’s large-scale in vivo target discovery platform.  Most recently, Dr. Zambrowicz served as Lexicon’s executive vice president of research, where he was responsible for scientific operations spanning target discovery to clinical candidate selection for both small molecule and antibody therapeutics.  Dr. Zambrowicz is also responsible for managing Lexicon’s strategic alliances, including those with Bristol-Myers Squibb Company, Genentech, Inc., N.V. Organon, and Takeda Pharmaceutical Company Limited.  Before joining Lexicon, Dr. Zambrowicz was an NIH postdoctoral fellow at The Fred Hutchinson Cancer Center in Seattle, Washington, where he studied gene trapping and gene targeting technology.  Dr. Zambrowicz received his B.S. in Biochemistry from the University of Wisconsin and his Ph.D. from the University of Washington, where he studied tissue-specific gene regulation using transgenic mice.

Dr. Main, who joined Lexicon in July 2001 through its acquisition of Coelacanth Corporation, has led the Company’s growth into small molecule drug discovery and development based on targets discovered in the Genome5000™ program.  Most recently, Dr. Main served as senior vice president of Lexicon Pharmaceuticals, where he established Lexicon’s medicinal chemistry capabilities.  Dr. Main is also responsible for managing Lexicon’s site operations in Princeton, New Jersey.  Dr. Main was formerly senior vice president, U.S. research at Novartis Pharmaceuticals Corporation, where he worked for 20 years before joining Coelacanth as its chief executive officer.  Dr. Main received a B.S. from the University of Aberdeen, Scotland and a Ph.D. in organic chemistry from the University of Liverpool, England and completed postdoctoral studies at the Woodward Research Institute.

About Lexicon
Lexicon is a biopharmaceutical company focused on the discovery and development of breakthrough treatments for human disease.  Lexicon currently has clinical programs underway for such areas of major unmet medical need as irritable bowel syndrome and cognitive disorders.  The company has used its proprietary gene knockout technology to discover more than 100 promising drug targets and create an extensive pipeline of clinical and preclinical programs in the therapeutic areas of diabetes and obesity, cardiovascular disease, psychiatric and neurological disorders, cancer, immune system disorders and ophthalmic disease.  To advance the development and commercialization of its programs, Lexicon is working both independently and through collaborators which include Bristol-Myers Squibb Company, Genentech, Inc., N.V. Organon and Takeda Pharmaceutical Company Limited.  For additional information about Lexicon and its programs, please visit www.lexicon-genetics.com.

Safe Harbor Statement
This press release contains “forward-looking statements,” including statements relating to Lexicon’s growth and future operating results, discovery and development of products, strategic alliances and intellectual property, as well as other matters that are not historical facts or information.  All forward-looking statements are based on management’s current assumptions and expectations and involve risks, uncertainties and other important factors, specifically including those relating to Lexicon’s ability to successfully conduct preclinical and clinical development of its potential drug candidates, advance additional candidates into preclinical and clinical development, obtain necessary regulatory approvals, achieve its operational objectives, obtain patent protection for its discoveries and establish strategic alliances, as well as additional factors  relating to manufacturing, intellectual property rights, and the therapeutic or commercial value of its drug candidates, that may cause Lexicon’s actual results to be materially different from any future results expressed or implied by such forward-looking statements.  Information identifying such important factors is contained under “Factors Affecting Forward-Looking Statements” and “Business – Risk Factors” in Lexicon’s annual report on Form 10-K for the year ended December 31, 2005, as filed with the Securities and Exchange Commission.  Lexicon undertakes no obligation to update or revise any such forward-looking statements, whether as a result of new information, future events or otherwise.