EXHIBIT 5.1


                [Letterhead of Wachtell, Lipton, Rosen & Katz]





                                 August 28, 1997


CUC International Inc.
707 Summer Street
Stamford, Connecticut  06901

                  Re:  Registration Statement on Form S-4 of
                       CUC International Inc.

Ladies and Gentlemen:

                  We have acted as special counsel to CUC International Inc.,
a Delaware corporation ("CUC"), in connection with the above captioned
Registration Statement on Form S-4 (the "Registration Statement") being filed
today with the Securities and Exchange Commission (the "Commission") under the
Securities Act of 1933, as amended (the "1933 Act"), with respect to the
shares of common stock, par value $.01 per share, of CUC (the "CUC Shares")
proposed to be issued in connection with the merger (the "Merger") of HFS
Incorporated, a Delaware corporation ("HFS"), with and into CUC upon the terms
and subject to the conditions of the Agreement and Plan of Merger (the "Merger
Agreement"), dated as of May 27, 1997, filed as Exhibit 2.1 to the
Registration Statement, between CUC and HFS.

                  In connection with this opinion, we have examined the
Amended and Restated Certificate of Incorporation and Amended and Restated
By-Laws of CUC in the respective forms contemplated to be in effect at the
time that the CUC Shares are issued, the Registration Statement and the
exhibits thereto, and we have examined originals or copies, certified or
otherwise identified to our satisfaction, of such corporate records,
agreements, certificates of public officials and of officers of CUC and other
instruments, and such matters of law and fact as we have deemed necessary to
render the opinion contained herein.

                  In giving the opinion contained herein, we have with your
approval relied upon representations of officers of CUC and certificates of
public officials with respect to the accuracy of the material factual matters
addressed by such representations and certificates. We have, with your
approval, 





CUC International Inc.
August 28, 1997
Page 2





assumed the genuineness of all signatures or instruments submitted to us,
and the conformity of certified copies submitted to us with the original
documents to which such certified copies relate.

                  We are members of the Bar of the State of New York and we
express no opinion as to the laws of any jurisdiction other than the federal
laws of the United States, the General Corporation Law of the State of
Delaware and the laws of the State of New York.

         Based upon the foregoing, and assuming (i) the certificates
representing the CUC Shares will be manually signed by one of the authorized
officers of Boston EquiServe Limited Partnership, as transfer agent and
registrar (the "Transfer Agent and Registrar"), and registered by the Transfer
Agent and Registrar, (ii) the consummation of the Merger as contemplated by
the Merger Agreement, and (iii) that the shares of HFS common stock to be
exchanged for CUC Shares in the Merger have been validly issued, fully paid
and non-assessable, we are of the opinion that, upon the amendment of the
Amended and Restated Certificate of Incorporation of CUC to authorize a
sufficient number of shares of the common stock of CUC, and upon the Merger
having been approved by the stockholders of CUC and becoming effective
pursuant to the General Corporation Law of the State of Delaware, all as
described in the Registration Statement and any amendments thereto, the CUC
Shares will be duly authorized and, when issued in the manner described in the
Registration Statement and any amendments thereto, will be validly issued,
fully paid, and non-assessable.

                  We hereby consent (i) to the filing of this opinion with the
Commission as an exhibit to the Registration Statement and (ii) to the
statement made in reference to our firm under the caption "LEGAL MATTERS" in
the Joint Proxy Statement/Prospectus which is made a part of the Registration
Statement. We do not hereby admit by giving this consent that we are in the
category of persons whose consent is required under Section 7 of the 1933 Act.

                                              Very truly yours,

                                              /s/Wachtell, Lipton, Rosen & Katz