CUC INTERNATIONAL INC. AND SUBSIDIARIES EXHIBIT 15 -- LETTER RE: UNAUDITED INTERIM FINANCIAL INFORMATION August 27, 1997 Shareholders and Board of Directors CUC International Inc. We are aware of the incorporation by reference in the Joint Proxy Statement filed by CUC International Inc. and HFS Incorporated that is made a part of the Registration Statement (Form S-4) and related Prospectus of CUC International Inc. for the registration of its common stock of our report dated June 13, 1997 relating to the unaudited condensed consolidated interim financial statements of CUC International Inc. that are included in its Quarterly Report on Form 10-Q for the quarter ended April 30, 1997. Pursuant to Rule 436(c) of the Securities Act of 1933, our report is not a part of the registration statement prepared or certified by accountants within the meaning of Section 7 or 11 of the Securities Act of 1933. /s/ ERNST & YOUNG LLP ERNST & YOUNG LLP Stamford, Connecticut