EXHIBIT 99.1



                       LEXICON GENETICS ELECTS BARRY MILLS
                              TO BOARD OF DIRECTORS

THE WOODLANDS, TEXAS, JUNE 21, 2006 - Lexicon Genetics Incorporated (Nasdaq:
LEXG) announced today that Barry Mills, J.D., Ph.D. has been elected to its
Board of Directors.

Dr. Mills has been the president of Bowdoin College in Brunswick, Maine since
2001. He previously spent more than 20 years as an attorney with Debevoise &
Plimpton LLP in New York, where he focused on corporate law, real estate and
corporate finance and served as the firm's deputy presiding partner. He
currently serves on the board of directors of Maine Bank & Trust Co., a Maine
bank subsidiary of Chittenden Bank, and Galileo Fund Management Limited, as well
as several philanthropic boards. Dr. Mills earned an A.B. in biochemistry and
government from Bowdoin College, a Ph.D. in biology from Syracuse University and
a J.D. from the Columbia University School of Law.

"With the election of Dr. Mills to Lexicon's board of directors, we add
considerable independent governance, financial and legal expertise," said Arthur
T. Sands, M.D., Ph.D., president and chief executive officer of Lexicon.
"Lexicon will benefit from Dr. Mills' experience and insight as we continue our
advancement to drug development and commercialization."


ABOUT LEXICON GENETICS

Lexicon Genetics is a biopharmaceutical company focused on discovering and
developing breakthrough treatments for human disease. Lexicon is systematically
discovering the physiological and behavioral functions of genes to identify
potential points of therapeutic intervention, or drug targets. Lexicon makes
these discoveries using its proprietary gene knockout technology to model the
physiological effects that could be expected from prospective drugs addressing
these targets. For targets that the company believes have high pharmaceutical
value, it engages in programs for the discovery and development of small
molecule, antibody and protein drugs. Lexicon has advanced knockout-validated
targets into drug discovery programs in six therapeutic areas: diabetes and
obesity, cardiovascular disease, psychiatric and neurological disorders, cancer,
immune system disorders and ophthalmic disease. Lexicon is working both
independently and through collaborations and strategic alliances to accelerate
the development and commercialization of its discoveries.


SAFE HARBOR STATEMENT

This press release contains "forward-looking statements," including statements
about 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. These 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
development of its drug candidates and advance such candidates into clinical
development, achieve its operational objectives, obtain patent protection for
its discoveries and establish strategic alliances, as well as those relating to
manufacturing, the regulatory process, 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.

                                      # # #

CONTACT FOR LEXICON GENETICS:
Bobbie Faulkner
Manager, Investor Relations
281/863-3503
bfaulkner@lexgen.com