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                                                                    EXHIBIT 99.1

                  LEXICON GENETICS REPORTS 2004 FOURTH QUARTER
                         AND FULL YEAR FINANCIAL RESULTS

                   LEXICON ACHIEVES 44% ANNUAL REVENUE GROWTH

THE WOODLANDS, TEXAS, FEBRUARY 24, 2005 - Lexicon Genetics Incorporated (Nasdaq:
LEXG), a biopharmaceutical company focused on the discovery and development of
breakthrough treatments for human disease, today reported financial results for
the three months and year ended December 31, 2004.

REVENUES: Lexicon's revenues for the three months ended December 31, 2004
increased 90 percent to $26.0 million from $13.7 million for the corresponding
period in 2003. The increase was primarily attributable to the completion of the
third performance milestone under Lexicon's therapeutic protein and antibody
target discovery alliance with Genentech, Inc., together with revenues
recognized under Lexicon's neuroscience drug discovery alliance with
Bristol-Myers Squibb Company and its hypertension drug discovery alliance with
Takeda Pharmaceutical Company. For the year ended December 31, 2004, revenues
increased 44 percent to $61.7 million from $42.8 million in 2003. Collaborative
research represented 81 percent of Lexicon's revenues in 2004, as compared to 50
percent in 2003.

RESEARCH AND DEVELOPMENT EXPENSES: Research and development expenses for the
three months ended December 31, 2004 increased 14 percent to $23.1 million from
$20.3 million for the corresponding period in 2003. The increase primarily
reflects higher personnel, contract research and laboratory supply costs related
to the advancement of the Company's drug discovery programs. There was no
material stock-based compensation expense in the three months ended December 31,
2004, as compared to $1.2 million in the three months ended December 31, 2003.
For the year ended December 31, 2004, research and development expenses
increased ten percent to $90.6 million from $82.2 million in 2003. Research and
development expenses included non-cash, stock-based compensation expense of $0.4
million and $5.0 million for the years ended December 31, 2004 and 2003,
respectively.

GENERAL AND ADMINISTRATIVE EXPENSES: General and administrative expenses for the
three months ended December 31, 2004 decreased 24 percent to $4.3 million from
$5.7 million for the corresponding period in 2003. The decrease was primarily
attributable to the absence of any stock-based compensation expense in the three
months ended December 31, 2004, as compared to $1.2 million in the three months
ended December 31, 2003. For the year ended December 31, 2004, general and
administrative expenses decreased 20 percent to $18.6 million from $23.2 million
in 2003. General and administrative expenses included non-cash, stock-based
compensation expense of $0.4 million and $5.1 million for the years ended
December 31, 2004 and 2003, respectively.

NET LOSS: Net loss for the three months ended December 31, 2004 decreased to
$0.5 million from a net loss of $14.9 million in the corresponding period of
2003. Net loss per share for the three months ended December 31, 2004 was $0.01,
as compared to $0.24 for the corresponding period in 2003. For the year ended
December 31, 2004, net loss decreased to $47.2 million from a net loss of $64.2
million in 2003. Net loss per share for the year ended December 31, 2004 was
$0.74, compared to $1.13 for 2003. Net loss for the three months and the year
ended December 31, 2003 included a one-time, non-cash charge of $3.1 million for
the cumulative effect of a change in accounting principle.

CASH AND INVESTMENTS: As of December 31, 2004, Lexicon had $87.6 million in cash
and investments, including restricted cash and investments, as compared to $97.7
million as of September 30, 2004 and $161.0 million as of December 31, 2003.
Unrestricted cash and investments were $87.1 million at December 31, 2004, as
compared to $97.2 million at September 30, 2004 and $103.5 million at
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December 31, 2003. Lexicon used $20.8 million in cash in connection with the
refinancing of the synthetic lease of its headquarters and research facility in
The Woodlands, Texas in April 2004. This transaction eliminated all restrictions
on the cash and investments that had secured Lexicon's obligations under the
synthetic lease.

"Lexicon continues to be in a healthy financial position. In 2004, we grew
revenues for the ninth consecutive year and narrowed our net loss by $17
million," said Julia P. Gregory, executive vice president, corporate development
and chief financial officer of Lexicon. "Our revenues from our productive drug
discovery and development collaborations continue to grow at a faster rate than
the increases in operating expenses that we incur as we advance our programs
toward clinical development."

YEAR 2004 HIGHLIGHTS

DISCOVERY OF POTENTIAL THERAPIES FOR CANCER AND BLEEDING DISORDERS: Lexicon
advanced two of its drug discovery programs into preclinical development in
preparation for investigational new drug (IND) applications. The first, LX-1521,
is a small molecule compound to be developed as a potential cancer treatment.
The second, LX-5431, is a protein to be developed as a potential biotherapeutic
for thrombocytopenia, a condition that results in bleeding disorders.

LX-1521 is a novel small molecule compound with potential for treating solid
tumor cancers. LX-1521 works by blocking the cell cycle prior to cell division,
resulting in cancer cell death through apoptosis. Lexicon expects to file an IND
for LX-1521 by the end of the year and commence a Phase 1 clinical trial for the
compound shortly thereafter. LX-5431 is a novel recombinant human protein with
the potential for treating thrombocytopenia, a disorder characterized by a lack
of platelets in the blood that can lead to severe bleeding. LX-5431 has been
demonstrated in ex vivo bone marrow culture to stimulate production of platelet
forming cells called megakaryocytes. During 2005, Lexicon expects to develop
scale-up methodologies to produce LX-5431 in quantities required for preclinical
and early clinical development.

HARVESTED NOVEL DISCOVERIES FROM GENOME5000(TM) PROGRAM: Lexicon's Genome5000
program for drug discovery continued to yield novel drug discovery programs. In
this program, Lexicon is analyzing 5,000 genes using its proprietary gene
knockout technologies and its extensive physiological and behavioral analyses to
discover novel drug targets from the human genome. To date, Lexicon has
completed the analysis of more than forty percent of these genes and has
harvested more than 60 drug discovery programs.

ESTABLISHED COLLABORATION TO DISCOVER NEW DRUGS FOR HIGH BLOOD PRESSURE: In July
2004, Lexicon and Takeda formed a collaboration to discover new drugs for the
treatment of high blood pressure. In the collaboration, Takeda will have
exclusive access to drug targets from Lexicon's Genome5000 program that control
blood pressure. Takeda is responsible for all activities related to the
discovery, development and commercialization of drugs directed against these
targets, and will bear all related costs. Lexicon received an initial payment of
$12 million from Takeda for the three-year term of the agreement. Takeda will
make research milestone payments to Lexicon for each target selected for
therapeutic development. In addition, Takeda will make clinical development and
product launch milestone payments to Lexicon for each product commercialized
from the collaboration. Lexicon will also earn royalties on worldwide sales of
drugs commercialized by Takeda from the alliance.

ACHIEVED TWO PERFORMANCE MILESTONES IN GENENTECH ALLIANCE: Lexicon announced the
achievement of the second and third performance milestones under its alliance
with Genentech. In this alliance, Lexicon is discovering the functions of
potential therapeutic proteins and antibody targets identified through
Genentech's internal drug discovery research. The milestone payments are related
to Lexicon's
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production of gene knockouts in mouse embryonic stem cell lines for all of the
proteins selected for inclusion in the alliance and the identification of the
physiological functions of one half of the proteins in the alliance. Lexicon is
in the process of discovering the therapeutic potential for the remaining
proteins. The amounts of the milestone payments were not disclosed.

AWARDED BIODEFENSE GRANT FROM THE UNITED STATES ARMY: Lexicon was awarded a
grant from the United States Army Medical Research Institute of Infectious
Diseases (USAMRIID) for the discovery of novel drug targets that could provide
resistance to ricin poisoning. Lexicon will use its proprietary gene knockout
technology to study genes that, when blocked, may confer resistance to the toxic
effects of ricin exposure. Identification of the proteins, or host factors,
involved in toxin action may enable the development of drugs designed to block
these factors, with the goal of rendering an organism temporarily resistant to
ricin. Lexicon will receive $1.9 million in funding for the one-year initial
term of the grant.

GRANTED INTERNAL RESEARCH LICENSES TO PATENTED GENE TARGETING TECHNOLOGY:
Lexicon granted one new sublicense under patents covering its gene targeting
technologies and renewed another, further demonstrating the importance of in
vivo target validation in drug discovery. Lexicon granted a non-exclusive,
internal research-use sublicense under the patents to Johnson & Johnson
Pharmaceutical Research & Development, L.L.C. (J&JPRD), a Johnson & Johnson
Company, and renewed a sublicense for Roche Palo Alto, L.L.C. Both licenses
provide rights under patents covering the technologies frequently referred to as
"isogenic DNA" and "positive-negative selection" to generate and use knockout
mice in internal drug discovery.

"In 2004, Lexicon moved two novel programs into preclinical development,
representing the beginning of the advancement of our more than 60 drug discovery
programs toward human clinical trials. We expect to identify several additional
clinical candidates in 2005," said Arthur T. Sands, M.D., Ph.D., president and
chief executive officer of Lexicon. "With the achievement of two performance
milestones under our Genentech collaboration and the formation of our Takeda
alliance, we also demonstrated strong progress in drug discovery and development
through our collaborations."

LEXICON CONFERENCE CALL:

Dr. Arthur T. Sands, president and chief executive officer, and Julia P.
Gregory, executive vice president, corporate development and chief financial
officer, will host a conference call at 11:00 a.m. EST on Thursday, February 24,
2005 to review Lexicon's operating highlights and financial results for the year
ended December 31, 2004 and to discuss the company's guidance for 2005.

The dial-in number for the conference call is 800-500-0177 (within the United
States) or 719-457-2679 (international). The pass code for all callers is
3403652. Investors can access www.lexicon-genetics.com to listen to a live
webcast of the call. The webcast will be archived and available for review
through March 1, 2005.

ABOUT LEXICON GENETICS

Lexicon Genetics is a biopharmaceutical company focused on the discovery and
development of 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
directed against novel targets. The Company has advanced knockout-validated
targets into drug discovery programs in six therapeutic areas: diabetes and
obesity, cardiovascular disease, cancer, immune system disorders, ophthalmic
disease, and
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psychiatric and neurological disorders. Lexicon is working both independently
and through strategic collaborations and alliances to accelerate the development
and commercialization of its discoveries. Additional information about Lexicon
is available through its corporate website, www.lexicon-genetics.com.

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, 2003, 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
281/863-3505
bfaulkner@lexgen.com

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                          LEXICON GENETICS INCORPORATED

                             SELECTED FINANCIAL DATA

<Table>
<Caption>
                                                                                  ---------------------     -----------------------
                                                                                   THREE MONTHS ENDED            YEAR ENDED
                                                                                       DECEMBER 31,              DECEMBER 31,
CONSOLIDATED STATEMENTS OF OPERATIONS DATA                                        ---------------------     -----------------------
(In thousands, except per share data)                                               2004         2003         2004          2003
                                                                                  --------     --------     ---------     ---------
                                                                                       (UNAUDITED)         (UNAUDITED)
<S>                                                                               <C>          <C>          <C>           <C>
Revenues:
    Subscription and license fees ............................................    $  4,272     $  6,109     $  12,004     $  21,550
    Collaborative research ...................................................      21,739        7,577        49,736        21,242
    Other ....................................................................          --           14            --            46
                                                                                  --------     --------     ---------     ---------
      Total revenues .........................................................      26,011       13,700        61,740        42,838
Operating expenses:
   Research and development, including stock-based compensation
       of $11, $1,247, $426 and $5,048, respectively .........................      23,120       20,346        90,586        82,198
   General and administrative, including stock-based compensation
       of $0, $1,240, $412 and $5,067, respectively ..........................       4,349        5,695        18,608        23,233
                                                                                  --------     --------     ---------     ---------
      Total operating expenses ...............................................      27,469       26,041       109,194       105,431
                                                                                  --------     --------     ---------     ---------
Loss from operations .........................................................      (1,458)     (12,341)      (47,454)      (62,593)
Interest income ..............................................................         440          404         1,638         1,555
Interest expense .............................................................        (831)         (85)       (2,660)         (325)
Other income .................................................................       1,308          222         1,304           241
                                                                                  --------     --------     ---------     ---------
Net loss before cumulative effect of a change in accounting principle ........        (541)     (11,800)      (47,172)      (61,122)
Cumulative effect of a change in accounting principle ........................          --       (3,076)           --        (3,076)
                                                                                  --------     --------     ---------     ---------
Net loss .....................................................................    $   (541)    $(14,876)    $ (47,172)    $ (64,198)
                                                                                  ========     ========     =========     =========
Net loss per common share, basic and diluted:
Net loss before cumulative effect of a change in accounting principle ........    $  (0.01)    $  (0.19)    $   (0.74)    $   (1.08)
Cumulative effect of a change in accounting principle ........................          --        (0.05)           --         (0.05)
                                                                                  --------     --------     ---------     ---------
Net loss per common share, basic and diluted .................................    $  (0.01)    $  (0.24)    $   (0.74)    $   (1.13)
                                                                                  ========     ========     =========     =========

Shares used in computing net loss per common share ...........................      63,449       62,794        63,327        56,820
</Table>

<Table>
<Caption>
                                                                                     -----------------------------------------
CONSOLIDATED BALANCE SHEET DATA                                                       AS OF DECEMBER 31,    AS OF DECEMBER 31,
(In thousands)                                                                              2004                  2003
                                                                                     -------------------    ------------------
                                                                                         (UNAUDITED)
<S>                                                                                      <C>                   <C>
Cash and investments, including restricted cash and investments of
    $430 and $57,514, respectively ...........................................           $  87,558             $ 161,001
Property and equipment, net ..................................................              84,573                83,676
Goodwill .....................................................................              25,798                25,798
Intangible assets other than goodwill, net ...................................               1,840                 3,040
Total assets .................................................................             211,980               284,199
Deferred revenue .............................................................              37,592                47,692
Current and long-term debt ...................................................              37,631                56,344
Accumulated deficit ..........................................................            (261,115)             (213,943)
Total stockholders' equity ...................................................             121,594               166,216
</Table>
