IsoRay, Inc. to be listed on the American Stock Exchange; Shares to Trade Under the Symbol ISR

Company focuses on brachytherapy solutions for prostate cancer and other malignant tissue cancers with proprietary Cesium-131 radioisotope

Richland, WA -- Monday, April 16, 2007 -- RICHLAND, WA— IsoRay, Inc. (OTC Bulletin Board: ISRY) today announced that its common stock has been approved for listing on the American Stock Exchange ® (AMEX®). IsoRay’s common stock is expected to commence listing on the American Stock Exchange under the ticker symbol ISR on Thursday, April 19, 2007.

IsoRay, Inc. ("IsoRay") is a medical isotope company that focuses 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 the Cesium-131 brachytherapy seed currently used to treat prostate cancer.

"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 company recently completed $16,500,000 in financing led by Punk, Ziegel & Co. and Maxim Group LLC on March 22, 2007.

This approval is contingent upon IsoRay being in compliance with all the applicable listing standards on the date it begins trading on the exchange, and may be rescinded if IsoRay is not in compliance with such standards.

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

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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