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                               EXHIBIT NUMBER 5.1


                     [RUTTER, HOBBS & DAVIDOFF INCORPORATED]

                                  July 26, 2001




Advanced Biotherapy, Inc.
6355 Topanga Canyon Boulevard
Woodland Hills, California 91367

Gentlemen:

        We are counsel for Advanced Biotherapy, Inc., a Delaware corporation
(the "Company"), and are acting as such in connection with the filing of a
registration statement on Form S-3 (including all amendments thereto, the
"Registration Statement") under the Securities Act of 1933, as amended (the
"Securities Act"), with respect to the registration of 8,999,642 shares of the
Company's common stock, par value $.001 per share ("Common Stock"), that may be
issued in connection with the conversion of convertible subordinated debt due
September 30, 2004 ("Convertible Debt") presently outstanding or which hereafter
may be issued by the Company as interest payments (in lieu of cash payments),
and with respect to an additional 4,685,135 shares issuable upon exercise of
certain warrants ("Warrants") granted by the Company (all 13,684,777 shares
covered by the Registration Statement referred to herein as "Shares").

        We have examined and considered all such documents, corporate records,
certificates of public officials, and other instruments as we have deemed
necessary or appropriate for the purposes of the opinion set forth below. In
addition to the examination outlined above, we have conferred with various
officers of the Company and have ascertained or verified to our satisfaction
such additional facts as we deem necessary or appropriate for the purposes of
this opinion. We have assumed, with your permission, that the holders of the
Convertible Debt validly exercise their respective conversion rights to acquire
Shares in accordance with the terms thereof and that the holders of the Warrants
validly exercise their respective purchase rights to acquire Shares in
accordance with the terms thereof. We call your attention to the fact that our
opinion is limited to facts as they exist on the date hereof, and we disclaim
any undertakings to advise you of changes which hereafter may be brought to our
attention.

        Based on the foregoing, we are of the opinion that the Shares have been
duly authorized, and, upon due conversion and due exercise, as applicable, will
be validly


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issued and non-assessable.

        Members of our firm are admitted to the practice of law in the State of
California and we express no opinions as to the laws of any jurisdiction other
than the laws of the State of California and the General Corporation Law of the
State of Delaware. We hereby consent to the references to our firm in the
Registration Statement and to the filing of this opinion by the Company as an
exhibit to the Registration Statement. In giving this consent, we do not hereby
admit that we come within the category of persons whose consent is required
under Section 7 of the Securities Act or the rules and regulations of Securities
and Exchange Commission thereunder.

                                       Very truly yours,




                                       RUTTER, HOBBS & DAVIDOFF
                                       INCORPORATED

