AMERICAN STOCK EXCHANGE LISTS THE COMMON STOCK OF ISORAY, INC.

New York, April 19, 2007 — The American Stock Exchange® (Amex®) today listed the common stock of IsoRay, Inc. under the ticker symbol ISR.

IsoRay, Inc. is a medical isotope company focusing on brachytherapy solutions for prostate cancer and other malignant tissue cancers through use of its proprietary Cesium-131 radioisotope.  Cesium-131 is the most significant scientific advancement in prostate cancer brachytherapy in more than 20 years. IsoRay, Inc., through its subsidiary, IsoRay Medical, Inc., produces and sells the Cesium-131 brachytherapy seed currently used to treat prostate cancer.

“IsoRay, Inc. does important work in the field of cancer therapy, and the American Stock Exchange is pleased to list their shares,” said John McGonegal, Senior Vice President of Amex’s Equities Group. “We expect IsoRay will find itself in good company among the increasing number of innovative medical technology companies that have chosen to list at the Amex.”

"This listing represents another important milestone for IsoRay and its shareholders,” said Roger Girard, Chairman and CEO of IsoRay, Inc. “We believe that listing our shares on the American Stock Exchange will improve the visibility of IsoRay as well as increase the liquidity of its shares.”

The specialist in IsoRay, Inc. will be Kellogg Capital Group. For further information on ISR and other Amex-listed companies, please visit www.amex.com.

About IsoRay

IsoRay, Inc., through its subsidiary, IsoRay Medical, Inc., is the sole producer of the Cesium-131 brachytherapy seed, used to treat prostate and other cancers. The Cesium-131 seed offers a significantly shorter half-life than the two other isotopes commonly used for brachytherapy, which results in a substantially faster delivery of therapeutic radiation, lower probability of cancer cell survival and reduction of the longevity of common brachytherapy side effects(a)(b). IsoRay is based in Richland, Washington. More information is available about IsoRay at www.isoray.com.

• (a) Armpilia CI, Dale RG, Coles IP, et al. The Determination of Radiobiologically Optimized Half-lives for Radionuclides Used in Permanent Brachytherapy Implants. Int. J. Radiation Oncology Biol. Phys. 2003; 55 (2): 378-385.
• (b) Prestidge B.R., Bice W.S., Jurkovic I., et al. Cesium-131 Permanent Prostate Brachytherapy: An Initial Report. Int. J. Radiation Oncology Biol. Phys. 2005; 63 (1): 5336-5337

About American Stock Exchange

The American Stock Exchange® (Amex®) offers trading across a full range of equities, options and exchange traded funds (ETFs), including structured products and HOLDRSSM. In addition to its role as a national equities market, the Amex is the pioneer of the ETF, responsible for bringing the first domestic product to market in 1993. Leading the industry in ETF listings, the Amex lists 287 ETFs to date. The Amex is also one of the largest options exchanges in the U.S., trading options on broad-based and sector indexes as well as domestic and foreign stocks.

Safe Harbor Statement

Statements in this news release about IsoRay’s future expectations, including: the advantages of our Cesium-131 seed, the listing of the common stock on AMEX®, future production capabilities, development of protocols for the use of our Cesium-131 seed to treat cancers other than prostate cancer, the level of market share our seed may attain, and all other statements in this release, other than historical facts, are forward-looking statements. It is important to note that actual results and ultimate corporate actions could differ materially from those in such forward-looking statements based on such factors as physician acceptance, training and use of our products, listing standards on the day trading is scheduled to begin on AMEX®, and other risks detailed from time to time in IsoRay's reports filed with the SEC.

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