July 15, 2008

Dyax Enters into an Exclusive Negotiation Period With Dompe for European License to DX-88 in Angioedema Indications

Dyax Corp. (NASDAQ: DYAX) announced today that the Company has entered into an exclusive negotiation period ending on September 30, 2008 with Dompe Farmaceutici S.p.A. ("Dompe") for a European license to DX-88 in angioedema indications, including hereditary angioedema (HAE), for which the Company recently completed its second Phase 3 trial. As a condition for the exclusive negotiation rights, Dompe entered into a Securities Sale Agreement with Dyax to purchase 2,008,032 million shares of Dyax common stock in a private placement at $4.98 per share, which represents a 57% premium over the closing price on July 10, 2008. The offering, which represents a total investment of $10 million, is expected to close on July 17, 2008.

"We look forward to finalizing a partnership with Dompe for DX-88 in angioedema indications, and believe that their regulatory and commercial capabilities in Europe could add significantly to the DX-88 franchise worldwide," commented Henry E. Blair, Chairman, President and Chief Executive Officer of Dyax. "Dompe's premium, unconditional investment in Dyax highlights the value potential of the DX-88 franchise as well as our proprietary phage display discovery technology. This agreement, if finalized, will be another step towards the completion of our DX-88 global strategy, which also includes a partnership with Cubist Pharmaceuticals for surgical indications, and our own commercial infrastructure for hereditary angioedema within the U.S."

"We are very pleased to enter into this exclusive negotiation period with Dyax for a European license to DX-88 in angioedema indications, which represents a strategic opportunity for Dompe," stated Sergio Dompe, President of Dompe Farmaceutici S.p.A. "This agreement falls within a broader strategy aimed at the expansion of the Dompe Group at the international level, with a focus on developing its expertise in the area of rare diseases."

Mr. Dompe further commented, "While the discovery of rare diseases and their more accurate diagnosis is steadily increasing, there are still very few drugs available for their treatment. Through this investment with Dyax, the Dompe Group provides its contribution to the research and development of therapeutic solutions for unmet medical needs in the orphan drug arena."

The securities offered in this private placement have not been registered under the Securities Act of 1933, as amended or state securities laws, and cannot be offered or sold in the United States absent registration with the Securities and Exchange Commission or an applicable exemption from the registration requirements. This press release is neither an offer to sell nor a solicitation of an offer to buy any of the securities discussed herein and shall not constitute an offer, solicitation or sale in any jurisdiction in which such offer, solicitation or sale is unlawful.

About Dyax

Dyax is focused on advancing novel biotherapeutics for unmet medical needs, with an emphasis in oncology and inflammation. Dyax utilizes its proprietary drug discovery technology, phage display, to identify antibody, small protein and peptide compounds. Dyax, on its own or with its partners, has advanced several product candidates from discovery and lead validation into preclinical and clinical development. The Company's lead product candidate, DX-88, is a recombinant small protein that is being developed by Dyax for its therapeutic potential for treating hereditary angioedema (HAE). 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 HAE attacks. In April 2008, Dyax licensed to Cubist Pharmaceuticals the intravenous formulation of DX-88 for surgical indications in North America and Europe. In addition to using phage display for its internal pipeline, Dyax leverages this technology broadly into revenue generating licenses and collaborations through its Licensing and Funded Research Program (LFRP). Dyax is headquartered in Cambridge, Massachusetts. For more information about Dyax Corp., please visit www.dyax.com.

About Dompe

Dompe is a fully-integrated and leading Italian pharmaceutical and biotechnological company with commercialized products in more than 60 countries worldwide. The Company is capable of covering all the drug manufacturing stages and has developed competitive skills in research and innovation. With a focus on monoclonal antibodies, low molecular weight drugs and recombinant DNA, Dompe's success is a result of its dedicated structure dealing with the discovery of appropriate therapeutic opportunities for treating pathologies and unmet medical needs. Dompe's R&D and manufacturing site is well-known for its advanced research laboratories as well as biotechnological plants internationally validated for the production of fully-human monoclonal antibodies. Dompe's innovation is also characterized by an expanding network of alliances with international partners, with a growing commercial portfolio in Western and Eastern Europe. These alliances have enabled Dompe to enhance its capabilities in the regulatory and commercial areas. Dompe aims at fostering its pharmaceutical expertise by providing physicians with new therapeutic tools. Moreover, Dompe intends to extend its portfolio with orphan drugs, new advanced therapeutic solutions for cancers, nephropathies and other severe pathologies such as multiple sclerosis.

Dyax Disclaimer

This press release contains forward-looking statements, including statements regarding (i) the possible completion of a partnership with Dompe (ii) the closing of the private placement and (ii) the progress of ongoing clinical trials and the prospects for regulatory filings and approvals for DX-88. 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 prospects for regulatory filings for DX-88 include the risks that: (i) Dyax and Dompe are unable to reach an agreement during the exclusivity period, (ii) DX-88 may not show therapeutic effect or an acceptable safety profile in clinical trials or could take a significantly longer time to gain regulatory approval than Dyax expects or may never gain approval, (iii) others may develop technologies or products superior to DX-88, (iv) Dyax is dependent on the expertise, effort, priorities and contractual obligations of third parties in the clinical trials, manufacture, marketing, sales and distribution of its biopharmaceuticals, (v) DX-88 may not gain market acceptance; (vi) Dyax may not be able to obtain and maintain intellectual property protection for DX-88 for the duration of its patent covering DX-88, and (vii) other risk factors described or referred to in Dyax's most recent Annual Report on Form 10-K and other periodic reports filed from time to time 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 registered trademarks of Dyax Corp. EDEMA4 is a registered service mark of Dyax Corp.