Exhibit 5.1


        COVINGTON & BURLING

        1201 PENNSYLVANIA AVENUE             WASHINGTON
        WASHINGTON, DC  20004-2401           NEW YORK
        TEL  202.622.6000                    LONDON
        FAX  202.662.6291                    BRUSSELS
        WWW.COV.COM                          SAN FRANCISCO


                                                        May 10, 2001


Unigene Laboratories, Inc.
110 Little Falls Road
Fairfield, New Jersey 07004

Gentlemen:

     This opinion is being  furnished to you in connection  with a  Registration
Statement  on Form S-1  (the  "Registration  Statement")  being  filed  today by
Unigene  Laboratories,  Inc., a Delaware  corporation (the "Company"),  with the
Securities and Exchange Commission under the Securities Act of 1933, as amended,
for the  registration  for resale by Fusion  Capital Fund II, LLC  ("Fusion") of
9,000,000  shares of the Company's  common stock,  par value $.01 per share (the
"Common Stock"), consisting of:

     (a) up to 6,000,000  shares of Common Stock (the  "Purchase  Shares")  that
Fusion has agreed to purchase from the Company in accordance  under the terms of
a Common Stock Purchase Agreement,  dated as of May 9, 2001, between the Company
and Fusion (the "Common Stock Purchase Agreement),

     (b) 2,000,000 shares of Common Stock (the  "Compensation  Shares") that the
Company has issued to Fusion as compensation for its commitment, and

     (c)  1,000,000  shares of Common  Stock  (the  "Warrant  Shares")  that are
issuable  upon the exercise of a Warrant,  dated as of March 30, 2001,  that the
Company  has  issued to Fusion  (the  "Warrant")  also as  compensation  for its
commitment.

     For purposes of this opinion,  we have examined the Registration  Statement
and the relevant exhibits thereto, including:

          (1) the Common Stock Purchase Agreement,

          (2) a  Registration  Rights  Agreement,  dated as of April  23,  2001,
between the Company and Fusion, and

          (3) the Warrant.



                                       2

     COVINGTON & BURLING

     We also have examined and relied upon a copy of the  Company's  Certificate
of Incorporation,  certified by the Secretary of State of the State of Delaware,
and copies of the Company's By-Laws and certain resolutions adopted by the Board
of Directors of the Company,  each  certified by the Corporate  Secretary of the
Company.

     We  further  have  examined  such  other  documents  and  made  such  other
investigations  as we have  deemed  necessary  to form a basis  for the  opinion
hereinafter expressed. In examining the foregoing documents, we have assumed the
authenticity of documents  submitted to us as originals,  the genuineness of all
signatures, the conformity to original documents of documents submitted to us as
copies, and the accuracy of the representations and statements included therein.

     Based on the foregoing, we are of the opinion that:

     (1) the Purchase Shares have been duly authorized for issuance, and, if and
when issued,  sold and delivered by the Company to Fusion in accordance with the
terms of the Common Stock Purchase Agreement, will be validly issued, fully paid
and nonassessable

     (1) the  Compensation  Shares have been duly authorized and validly issued,
and are fully paid and nonassessable.

     (2) the Warrant Shares have been duly authorized for issuance,  and, if and
when issued,  sold and delivered by the Company to Fusion in accordance with the
terms of the Warrant, will be validly issued, fully paid, and nonassessable.

     We hereby  consent  to the  filing of this  opinion  as an  exhibit  to the
Registration  Statement  and to the use of our name  under  the  heading  "Legal
Matters" in the Prospectus forming a part thereof.


                                              Very truly yours,


                                              /s/ Covington & Burling
                                              -----------------------
                                              COVINGTON & BURLING