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                                                                    EXHIBIT 99.1

                                 (LEXICON LOGO)

                                                                    NEWS RELEASE
--------------------------------------------------------------------------------
FOR IMMEDIATE RELEASE

                           LEXICON GENETICS ANNOUNCES

                   PRICING OF COMMON STOCK IN PUBLIC OFFERING

THE WOODLANDS, TEXAS, JULY 23, 2003 - Lexicon Genetics Incorporated (Nasdaq:
LEXG) today announced the pricing of a public offering of 10.0 million shares of
its common stock at $5.25 per share. Net proceeds to the company are expected to
be approximately $49.0 million. All of the shares are being offered by Lexicon
under an effective shelf registration statement previously filed with the
Securities and Exchange Commission. The underwriters have a 30-day option to
purchase up to an additional 1.5 million shares of common stock from Lexicon to
cover over-allotments, if any.

The offering is being joint lead managed by Morgan Stanley & Co. Incorporated
and UBS Securities LLC. CIBC World Markets Corp. and Punk, Ziegel & Company,
L.P. are also serving as managing underwriters for the offering. Morgan Stanley
is serving as sole bookrunner for the offering.

This press release shall not constitute an offer to sell or the solicitation of
an offer to buy any securities. There shall not be any sale of these securities
in any jurisdiction in which such offer, solicitation or sale would be unlawful
prior to registration or qualification under the securities laws of any such
jurisdiction.

The shares of common stock may only be offered by means of a prospectus. Copies
of the final prospectus supplement and accompanying prospectus related to the
offering may be obtained by contacting Morgan Stanley & Co. Incorporated, 1585
Broadway, New York, NY 10036 or UBS Securities LLC, 299 Park Avenue, New York,
NY 10171.

ABOUT LEXICON GENETICS

Lexicon Genetics is a biopharmaceutical company focused on the discovery of
breakthrough treatments for human disease. Lexicon is using proprietary gene
knockout technology to systematically discover the physiological functions of
genes in mice and to identify which corresponding human genes encode potential
targets for therapeutic intervention. Lexicon focuses its discovery efforts in
five therapeutic areas--metabolic disorders, cardiovascular disease, cancer,
immune system disorders and neurological disorders.

SAFE HARBOR STATEMENT

This press release contains "forward-looking statements." These forward-looking
statements are based on management's current assumptions and expectations and
involve risks, uncertainties and other important factors. 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, 2002, 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.

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CONTACT FOR LEXICON GENETICS:
Chas Schultz, Director
Investor Relations and Financial Analysis
281/863-3421



