Dyax Corp. Issued Seventh U.S. Patent in Its Phage Display Patent Portfolio

Business Wire, May 1, 2007

CAMBRIDGE, Mass. -- Dyax Corp. (Nasdaq:DYAX) announced today that the United States Patent and Trademark office issued U.S. Patent No. 7,208,293, Dyax's seventh U.S. patent covering its proprietary protein display technology. This new patent provides Dyax with additional patent claims that cover methods for selecting binding proteins, such as antibodies, through the use of eukaryotic cell surface display. In addition to its seven U.S. patents, Dyax holds several issued patents for phage display in Canada, Israel, and Japan, with pending applications in other countries.

"This newly issued patent strengthens Dyax's already dominant patent portfolio position in the field of protein display," stated Dr. Ivana Magovcevic-Liebisch, Dyax's General Counsel and Executive Vice President of Administration. "Our broad technology platform continues to provide Dyax and our collaborators with the ability to develop novel compounds through both phage and yeast display."

About Dyax

Dyax is focused on advancing novel biotherapeutics for unmet medical needs, with an emphasis on oncology and inflammatory indications. Dyax utilizes its proprietary drug discovery technology to identify antibody, small protein and peptide compounds for clinical development.

Dyax's lead product candidate is DX-88, a recombinant small protein that is currently in clinical trials for its therapeutic potential in two separate indications. Dyax has successfully completed three Phase 2 trials and a Phase 3 trial of DX-88 for the treatment of hereditary angioedema (HAE). Dyax initiated its second Phase 3 trial, known as EDEMA4, in April 2007. DX-88 has orphan drug designation in the U.S. and E.U., as well as Fast Track designation in the U.S. for the treatment of acute attacks of HAE.

Additionally, Dyax has successfully completed a Phase 1/2 trial of DX-88 for the prevention of blood loss during on-pump coronary artery bypass graft (CABG) procedures. Dyax is initiating a Phase 2 trial for further development of DX-88 in on-pump cardiothoracic surgery (CTS), including CABG and heart valve replacement or repair procedures.

Dyax identified DX-88 and other compounds in its pipeline using its patented phage display technology, which rapidly selects compounds that bind with high affinity and specificity to therapeutic targets. Dyax leverages this technology broadly with over 70 revenue generating licenses and collaborations for therapeutic discovery, as well as in non-core areas such as affinity separations, diagnostic imaging, and research reagents.

Dyax is headquartered in Cambridge, Massachusetts, and has antibody discovery facilities in Liege, Belgium. For online information about Dyax Corp., please visit www.dyax.com.

Dyax Disclaimer

This press release contains forward-looking statements, including statements regarding the extent of Dyax's patent portfolio, clinical trials, and plans for the development of DX-88 for HAE and CTS. Statements that are not historical facts are based on Dyax's current expectations, beliefs, assumptions, estimates, forecasts and projections about the industry and markets in which Dyax competes. The statements contained in this release are not guarantees of future performance and involve certain risks, uncertainties and assumptions, which are difficult to predict. Therefore, actual outcomes and results may differ materially from what is expressed in such forward-looking statements. Important factors which may affect the extent of Dyax's patent portfolio and its potential for the identification of novel compounds include the risks that: Dyax may not be able to obtain and maintain intellectual property protection for its Phage Display technology; others may develop technologies superior to Dyax's Phage Display technology; and Dyax is subject to other risk factors described or referred to in Dyax's most recent Annual Report on Form 10-K and other periodic reports filed with the Securities and Exchange Commission. Dyax cautions investors not to place undue reliance on the forward-looking statements contained in this release. These statements speak only as of the date of this release, and Dyax undertakes no obligations to update or revise these statements, except as may be required by law.

Dyax and the Dyax logo are the registered trademarks of Dyax Corp.