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                                                                    EXHIBIT 5.1
                                                                    -----------

                               KANE KESSLER, P.C.
                           1350 AVENUE OF THE AMERICAS
                          NEW YORK, NEW YORK 10019-4896
                                 (212) 541-6222






                                 April 29, 1999




Securities and Exchange Commission
450 Fifth Street, N.W.
Washington, D.C.  20549

                  Re:      Abacus Direct Corporation
                           Registration Statement on Form S-8
                           ----------------------------------

Gentlemen:

               We have acted as special counsel to Abacus Direct Corporation, a
Delaware corporation (the "Company"), in connection with the preparation of a
Registration Statement on Form S-8 (the "Registration Statement") pertaining to
the registration by the Company under the Securities Act of 1933, as amended, of
an offering of up to an aggregate of 375,000 shares of the Company's Common
Stock, $.001 par value per share (the "Shares"), pursuant to the Amended and
Restated Abacus Direct Corporation 1996 Stock Option Plan, as amended (the
"Plan").

               We have made such legal and factual examinations and inquiries,
including an examination of originals or copies certified or otherwise
identified to our satisfaction, of such documents, corporate records and
instruments, as we have deemed necessary or appropriate for purposes of this
opinion. In our examination, we have assumed the genuineness of all signatures,
the authenticity of all documents submitted to us as originals, and the
conformity to authentic original documents of all documents submitted to us as
copies.



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Securities and Exchange Commission
April 29, 1999
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               We have assumed that the number of shares which the Company is
authorized to issue in its Certificate of Incorporation, as amended, exceeds the
sum of (i) the number of shares of the Company's Common Stock outstanding, (ii)
the number of shares of the Company's Common Stock held as treasury shares, and
(iii) the number of shares of the Company's Common Stock which the Company is
obligated to issue (or has otherwise reserved for issuance for any purposes), by
at least the number of shares which may be issued in connection with the Plan,
and we have assumed for purposes of our opinion herein that such condition will
remain true at all future times relevant to this opinion. We have also assumed
that the Company will cause certificates representing Shares issued in the
future to be properly executed and delivered and will take all other actions
appropriate for the due and proper issuance of such Shares. We have assumed for
purposes of this opinion that options issued under the Plan and the Shares
issuable upon exercise of such options have been duly authorized by all
necessary corporate action on the part of the Company and such options have been
duly authorized and granted under the Plan. We express no opinion regarding any
shares reacquired by the Company after initial issuance.

               We are members of the Bar of the State of New York and are not
admitted to practice law in any other jurisdiction. We do not hold ourselves out
as being conversant with, and express no opinion as to, the laws of any
jurisdiction other than the laws of the State of New York and the General
Corporation Law of the State of Delaware.

               Subject to the limitations stated in this letter, and subject
further to the following limitations, it is our opinion that the Shares issued
by the Company, upon due exercise of any option under and in accordance with the
Plan and any agreement pursuant to which such option was granted, will, upon
delivery thereof and receipt by the Company of all consideration owed to the
Company under the terms of the Plan and such agreement be validly issued, fully
paid and nonassessable.

               The foregoing assumes that the aforesaid Registration Statement
will become and remain effective under the Securities Act of 1933, as amended,
prior to any offering of the Shares pursuant to the terms thereof and will be
amended, as appropriate, and that there will be compliance with all applicable
state securities laws in connection with the offering of such securities, as
well as compliance with the terms of the offering set forth in the Registration
Statement.



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Securities and Exchange Commission
April 29, 1999
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               This opinion is rendered solely for your benefit and may not be
relied upon by any other person or entity. This opinion is provided to you as of
the date hereof. We undertake no, and hereby disclaim any obligation to advise
you of any change in any matter set forth herein. Without our prior written
consent, this opinion may not be quoted in whole or in part or otherwise
referred to in any report or document furnished to any person or entity.

               We consent to the filing of this letter as an exhibit to the
Registration Statement. 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 Securities Act of 1933, as amended, or the rules and regulations of the
Securities and Exchange Commission thereunder.


                                       Very truly yours,



                                       Kane Kessler, P.C.



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