CAMBRIDGE, MA
June 24, 2008

Tolerx, Inc., a biopharmaceutical company engaged in the discovery and development of novel therapies for the treatment of immune-mediated diseases, announced today that it has been named to the annual FierceBiotech “Fierce 15” list, designating it as one of the top biotech companies of 2008. The editors of FierceBiotech evaluated hundreds of privately-held firms based on company vision, revenue potential, quality of deals, strength of technology, partnerships, and competitive market position. Tolerx was determined to be one of the “fiercest,” proven by its creativity and innovations in the industry.

An internationally recognized daily newsletter reaching more than 65,000 biotech and pharma industry professionals, FierceBiotech provides subscribers with a quick authoritative briefing on the day’s top stories, with a special focus on drug discovery and clinical trials.

John Carroll, Editor of FierceBiotech, said, "A rich partnership pact with GlaxoSmithKline last October kept Tolerx in the race to develop an anti-CD3 monoclonal antibody for autoimmune disease. That program has now begun a Phase III clinical trial known as DEFEND, and all the chips are on the table."

"FierceBiotech is renowned for its advanced understanding of biotechnology companies and the industry as a whole," said Dr. Douglas J. Ringler, President and Chief Executive Officer of Tolerx. "Being selected as a member of the ‘Fierce 15’ is an honor that highlights Tolerx’s potential to make a significant impact in the biotech market.”

The Fierce 15 celebrates the spirit of being “fierce” – championing innovation and creativity, even in the face of intense competition. The complete list of ‘Fierce 15’ companies is available in today’s issue of FierceBiotech and on the FierceBiotech Web site at www.fiercebiotech.com.

Tolerx is a biopharmaceutical company engaged in the discovery and development of novel therapies for immune-mediated diseases. Tolerx currently has two antibodies in clinical development for the potential treatment of various autoimmune indications: otelixizumab, an anti-CD3 MAb which is being developed in collaboration with GlaxoSmithKline and a modified form of TRX1, which is being developed in collaboration with Genentech, Inc. Tolerx is also engaged in preclinical development of new product candidates that circumvent immune system tolerance. These product candidates are being evaluated for the treatment of cancer or chronic viral diseases. For more information, please visit www.tolerx.com.

Tolerx Forward-Looking Statements
This press release contains certain statements that include the word “potential”. Such statements, which are not historical facts, constitute “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995 (the “Reform Act”). Statements regarding outcomes sought to be realized in the clinical trials or preclinical development, and the potential for Tolerx to make a significant impact in the biotech market are all forward-looking statements. Such forward-looking statements involve risks, uncertainties and other factors that may cause the actual performance or achievements of Tolerx to be materially different from any future results, performance, or achievements expressed or implied by such forward-looking statements. There can be no certainty that Tolerx will advance any clinical candidate or other component of its pipeline to the clinic, to the next regulatory step or to commercialization or that Tolerx will ever realize revenue from commercialization of product candidates it is currently or may in the future seek to develop. Factors and risks that may impact management’s expectations and affect the forward-looking statements include but are not be limited to the sufficiency, scope and breath of the company’s vision, the strength of the company’s technology, the continuation, robustness and resilience of the company’s innovation and creativity, results of DEFEND and other future clinical studies, results of pre-clinical studies, the ability to obtain regulatory approval for advancement of any product candidate, the continuation of the collaborations with GSK and Genentech, the introduction of competing therapies by other companies and changes in the company’s business plan or objectives. These statements reflect the view of Tolerx as of the date of this press release and should not be relied upon as reflecting the company’s views at any date subsequent to this release. Tolerx undertakes no obligation to update or revise any forward-looking statements to reflect events or circumstances after the date of this press release.