Exhibit 5.1

                        SILVERMAN SCLAR SHIN & BYRNE PLLC
                        381 Park Avenue South, Suite 1601
                            New York, New York 10016
                              Tel. No. 212-779-8600

                        Telecopy Number - (212) 779-8858

                                                      September 13, 2004

Board of Directors
Hemispherx Biopharma, Inc.
1617 JFK Boulevard
Philadelphia, PA 19103

Re:   Hemispherx Biopharma, Inc. - Registration Statement on Form S-3
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Gentlemen:

We have acted as counsel for Hemispherx Biopharma, Inc., a Delaware corporation
(the "Company"), in connection with the preparation of the registration
statement on Form S-3 (the "Registration Statement") relating to the
registration under the Securities Act of 1933, as amended (the "Act"), of the
following shares of the Company's Common Stock, par value $0.001 per share (the
"Common Stock"): (i) an aggregate of 3,617,306 shares (the "Shares") issued to
investors on August 5, 2004 and (ii) an aggregate of 1,085,193 shares (the
"Warrant Shares") issuable upon exercise of certain outstanding warrants of the
Company issued on August 5, 2004 (the "Warrants"). The Shares and Warrant Shares
are to be offered and sold by certain securityholders of the Company (the
"Selling Stockholders").

We have reviewed and are familiar with such corporate proceedings and other
matters as we have deemed necessary for this opinion. Based upon the foregoing,
we are of the opinion that (i) the Warrant Shares to be offered and sold by the
Selling Stockholders have been duly authorized and, when issued by the Company
upon exercise of the Warrants in accordance with the Warrants, will be legally
issued, fully paid and nonassessable, and (ii) the Shares to be offered and sold
by the Selling Stockholders have been duly authorized, legally issued, fully
paid and nonassessable.

This opinion is limited to matters governed by the General Corporation Law of
the State of Delaware. No opinion is expressed as to the effect that the law of
any other jurisdiction may have upon the subject matter of the opinion expressed
herein under conflicts of law principles, rules and regulations or otherwise.

This opinion is limited to the specific issues addressed herein, and no opinion
may be inferred or implied beyond that expressly stated herein. We assume no
obligation to revise or supplement this opinion should the present laws of the
State of Delaware be changed by legislative action, judicial decision or
otherwise.

We hereby consent to the filing of this opinion as Exhibit 5.1 to the
Registration Statement and to the use of our name under the caption "Legal
Matters" in the Registration Statement and in the Prospectus included therein.
In giving this consent, we do not thereby admit that we are within the category
of persons whose consent is required under Section 7 of the Act or the rules and
regulations of the Securities and Exchange Commission promulgated thereunder.




This opinion is furnished to you in connection with the filing of the
Registration Statement and is not to be used, circulated, quoted or otherwise
relied upon for any other purposes.

                                           Very truly yours,

                                           /s/ Silverman Sclar Shin & Byrne PLLC
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                                           Silverman Sclar Shin & Byrne PLLC