EXHIBIT 5.1
                  [Oppenheimer Wolff & Donnelly LLP Letterhead]

January 18, 2002

BioSante Pharmaceuticals, Inc.
111 Barclay Boulevard, Suite 280
Lincolnshire, IL  60069

RE:      BIOSANTE PHARMACEUTICALS, INC.
         REGISTRATION STATEMENT ON FORM S-8

Ladies and Gentlemen:

We have acted as counsel to BioSante Pharmaceuticals, Inc., a Delaware
corporation (the "Company"), in connection with the Post-Effective Amendment No.
1 to the Registration Statement on Form S-8 to be filed by the Company with the
Securities and Exchange Commission (the "SEC") on the date hereof (the
"Post-Effective Amendment No. 1"). The Post-Effective Amendment No. 1 amends
that certain Registration Statement on Form S-8 filed by BioSante
Pharmaceuticals, Inc., a Wyoming corporation ("BioSante Wyoming"), with the SEC
on January 8, 2001 (the "Original Registration Statement"). The Post-Effective
Amendment No. 1 is being filed pursuant to Rule 414 under the Securities Act of
1933, as amended (the "Securities Act"), by the Company, which is the successor
to BioSante Wyoming, following a statutory merger of BioSante Wyoming with and
into the Company, with the Company as the surviving corporation, effective April
30, 2001 for the purpose of changing BioSante Wyoming's state of incorporation
to Delaware. The 7,000,000 shares of common stock, par value $0.0001 per share
(the "Common Stock"), of the Company issuable under the Company's 1998 Stock
Option Plan (the "Plan") pursuant to the Original Registration Statement, as
amended by the Post-Effective Amendment No. 1, are collectively referred to
herein as the "Shares." The term "Registration Statement" in this opinion refers
to the Registration Statement as amended by Post-Effective Amendment No. 1 and
as amended hereafter from time to time.

In acting as counsel for the Company and arriving at the opinions expressed
below, we have examined and relied upon originals or copies, certified or
otherwise identified to our satisfaction, of such records of the Company,
agreements and other instruments, certificates of officers and representatives
of the Company, certificates of public officials and other documents as we have
deemed necessary or appropriate as a basis for the opinions expressed herein. In
connection with our examination, we have assumed the genuineness of all
signatures, the authenticity of all documents tendered to us as originals, the
legal capacity of all natural persons and the conformity to original documents
of all documents submitted to us as certified or photostatic copies.

Based on the foregoing, and subject to the qualifications and limitations stated
herein, it is our opinion that:

1.   The Company has the corporate authority to issue the Shares in the manner
     and under the terms set forth in the Registration Statement.

2.   The Shares have been duly authorized and, when issued, delivered and paid
     for in accordance with the Plan as set forth in the Registration Statement,
     will be validly issued, fully paid and nonassessable.





We express no opinion with respect to laws other than those of the State of
Minnesota, the Delaware General Corporation Law and the federal laws of the
United States of America, and we assume no responsibility as to the
applicability thereto, or the effect thereon, of the laws of any other
jurisdiction.

We hereby consent to the filing of this opinion as Exhibit 5.1 to the
Registration Statement and to its use as part of the Registration Statement.

Very truly yours,

/s/ Oppenheimer Wolff & Donnelly LLP