FOR IMMEDIATE RELEASE


                   TANOX, INC. ADOPTS STOCKHOLDER RIGHTS PLAN

Houston (July 30, 2001) - Tanox, Inc. (Nasdaq: TNOX) announced today that its
Board of Directors has adopted a Rights Plan designed to protect Company
stockholders from coercive or unfair takeover techniques. Terms of the Rights
Plan provide for a dividend distribution of one Right for each outstanding share
of Common Stock to holders of record at the close of business on August 10,
2001.  The Rights Plan would be triggered if an acquiring party accumulates 20%
or more of the Company's Common Stock and would entitle holders of the Rights to
purchase either the Company's stock or shares in an acquiring entity at half of
market value.  The Company would generally be entitled to redeem the Rights at
$0.01 per Right at any time until the tenth day following the time the rights
become exercisable.  The Rights will expire on August 10, 2011.

Commenting on the Rights Plan, Dr. Nancy T. Chang, Tanox's President and Chief
Executive Officer, said, "The adoption of the Rights Plan is a means of
safeguarding against abusive takeover tactics and is not in response to any
accumulation of shares or hostile takeover attempt. The Board of Directors
believes that the Rights Plan represents a sound and reasonable means of
safeguarding the interests of the Company's stockholders. The Board of Directors
is not aware of any effort of any kind to acquire control of the Company."  Dr.
Chang said the Rights Plan is similar to those adopted by over 2000 other
companies, and that details of the new Rights Plan will be outlined in the
Company's Form 8-K filing with the SEC and a letter to be mailed to
stockholders.

Tanox, Inc. is a biopharmaceutical company with demonstrated expertise in
monoclonal antibody technology. The Company is engaged in the discovery and
development of therapeutic monoclonal antibodies designed to address significant
unmet medical needs in the areas of asthma, allergy, inflammation and other
diseases affecting the human immune system. Xolair, Tanox's most advanced
product in development, is an anti-immunoglobulin E, or anti-IgE, antibody which
is being developed for allergic asthma, seasonal allergic rhinitis (hay fever)
and perennial allergic rhinitis in collaboration with Novartis Pharmaceutical
Corporation and Genentech, Inc. Genentech and Novartis are collecting
information to respond to the complete response letter received from the U.S.
FDA on the marketing application submitted for Xolair for allergic asthma and
seasonal allergic rhinitis.  The information will also be provided to health
authorities in the EU, Switzerland, Australia and New Zealand to support
marketing applications filed there.

Statements in this press release about Tanox's products, including Xolair, and
their prospects for development and commercialization, other than statements of
historical facts, are forward-looking statements and are subject to a number of
uncertainties that may cause actual events or results to differ materially from
those suggested in the forward-looking statements. Factors that could affect
actual events or results include risks associated with obtaining regulatory
approval for and market acceptance of Tanox's products, performance by the
Company's present and


future collaboration partners, the outcome of pending litigation, the
uncertainty of preclinical and clinical testing results, the Company's limited
experience and capability in manufacturing and marketing the Company's products,
the Company's ability to enter into future collaborations, competition and
technological change, the strength of the Company's patent portfolio, the
Company's ability to manage growth and to attract and retain key personnel, the
Company's access to additional financings in the future, and existing and future
government regulations. Other risks that may affect Tanox include the
variability of royalty, license and other revenues, timelines that are subject
to change, and the unpredictability of decisions by the FDA and other regulatory
agencies, including decisions regarding whether sufficient data and compliance
with other requirements exist to support product licensure.

For further information contact:

Gregg B. Sloate - Associate Director of Investor Relations -- 713.578.4181
Isabel M. Cordova, The Trout Group - Investor Relations -- 212.477.9007 x13
Kelly Rose, BMC Communications - Media Relations --212.477.9007 x18