Hemispherx Biopharma Retires All Outstanding Debentures.

PHILADELPHIA -- Hemispherx Biopharma, Inc. (AMEX: HEB) announced today that the Company has retired all remaining debt related to convertible debentures issued in October 2003, January 2004 and July 2004. Of the outstanding debt of $4.1 million, only $ 1,643,960 was required to be paid in new funds to retire the debentures, with the balance being covered by other cash and securities already held as collateral for the debentures. At the close of the first quarter of 2007, the Company's cash and marketable securities totaled $24.6 million.

Retirement of the debentures releases Hemispherx Biopharma's assets from all collateral liens and terminates conversion rights for 2,001,907 shares of the Company's common stock.

Dr. William A. Carter, Chairman and CEO of Hemispherx, stated, "By paying off our debt we have taken another step forward in clearing the slate for execution of our business development strategy, which involves the pursuit of licensing and collaborative ventures that will advance our technologies towards commercialization."

About Hemispherx Biopharma

Hemispherx Biopharma, Inc. is a biopharmaceutical company engaged in the manufacture and clinical development of new drug entities for treatment of seriously debilitating disorders. Hemispherx's flagship products include Alferon N Injection[R] and the experimental therapeutics Ampligen[R] and Oragens[R]. Alferon N Injection[R] is approved for a category of STD infection, and Ampligen[R] and Oragens[R] represent experimental RNA nucleic acids being developed for globally important viral diseases and disorders of the immune system. Hemispherx's platform technology includes large and small agent components for potential treatment of various severely debilitating and life threatening diseases. Hemispherx has in excess of 100 patents comprising its core intellectual property estate, a fully commercialized product (Alferon N Injection[R]) and GMP certified manufacturing facilities for its novel pharma products. For more information please visit www.hemispherx.net

Information contained in this news release other than historical information, should be considered forward-looking and is subject to various risk factors and uncertainties. For instance, the strategies and operations of Hemispherx involve risk of competition, changing market conditions, change in laws and regulations affecting these industries and numerous other factors discussed in this release and in the Company's filings with the Securities and Exchange Commission. Any specifically referenced investigational drugs and associated technologies of the Company (including Ampligen[R], Alferon LDO and Oragens) are experimental in nature and as such are not designated safe and effective by a regulatory authority for general use and are legally available only through clinical trials with the referenced disorders. The forward-looking statements represent the Company's judgment as of the date of this release. The Company disclaims, however, any intent or obligation to update these forward-looking statements. Clinical trials for other potential indications of the approved biologic Alferon N Injection[R] do not imply that the product will ever be specifically approved commercially for these other treatment indications.