Exhibit 5.1

December 13, 2005


Novelos Therapeutics, Inc.
One Gateway Center, Suite 504
Newton, MA 02458

Ladies and Gentlemen:

     We are furnishing this opinion of counsel to Novelos Therapeutics, Inc., a
Delaware corporation (the "Company"), for filing as Exhibit 5.1 to Amendment No.
1 to the Registration Statement on Form SB-2/A (the "Registration Statement")
filed by the Company with the Securities and Exchange Commission under the
Securities Act of 1933, as amended, on December 13, 2005 relating to the resale
of up to 14,831,798 shares of the common stock, $0.0001 par value per share of
the Company (the "Shares").

     In arriving at the opinions expressed below, we have examined and relied on
the following documents: (a) the Certificate of Incorporation and Bylaws of the
Company, each as amended to date; (b) the Registration Statement; and (c) the
records of meetings and consents of the Board of Directors and stockholders of
the Company provided to us by the Company. In addition, we have examined and
relied on the originals or copies certified or otherwise identified to our
satisfaction of all such corporate records of the Company and such other
instruments and other certificates of public officials, officers and
representatives of the Company and such other persons, and we have made such
investigations of law, as we have deemed appropriate as a basis for the opinion
expressed below.

     Based upon the foregoing, and subject to the qualifications set forth
herein, we are of the opinion that when the Registration Statement shall have
become effective, (a) with respect to those Shares that are currently
outstanding, when sold pursuant to the Registration Statement, they will be
validly and legally issued, fully paid and non-assessable, and (b) with respect
to those Shares to be issued upon exercises of warrants, when such shares are
issued and sold pursuant to the Registration Statement, they will be validly and
legally issued, fully paid and non-assessable.

     We express no opinion as to the laws of any state or jurisdiction other
than the General Corporation Law of the State of Delaware (including applicable
provisions of the Delaware Constitution and reported judicial decisions
interpreting such Law and such Constitution) and the federal laws of the United
States of America.

     This opinion is being delivered and is intended for use solely in regard to
the transactions contemplated by the Registration Statement and may not be used,
circulated, quoted in whole or in part or otherwise referred to for any purpose
without our prior written consent and may not be relied upon by any person or
entity other than the Company, its successors and assigns. This opinion is based
upon our knowledge of law and facts as of its date. We assume no duty to
communicate to you with respect to any matter which comes to our attention
hereafter.



Novelos Therapeutics, Inc.
December 13, 2005
Page 2

     We consent to the filing of this opinion as an exhibit to the Registration
Statement and the reference to us under the heading "Legal Matters" in the
prospectus forming a part of the Registration Statement.


                                       Very truly yours,

                                       FOLEY HOAG LLP


                                       By: /s/ Paul Bork
                                           ----------------------------------
                                           A Partner