Exhibit 15
August 1, 2011
Wyndham Worldwide Corporation
22 Sylvan Way
Parsippany, New Jersey 07054
We have reviewed, in accordance with the standards of the Public Company Accounting Oversight Board
(United States), the unaudited interim financial information of Wyndham Worldwide Corporation and
subsidiaries for the periods ended June 30, 2011, and 2010, as indicated in our report dated August 1, 2011; because we did not perform an audit, we expressed no opinion on that information.
We are aware that our report referred to above, which is included in your Quarterly Report on Form
10-Q for the quarter ended June 30, 2011, is incorporated by reference in Registration Statement
No. 333-136090 on Form S-8 and Registration Statement No. 333-155676 on Form S-3.
We also are aware that the aforementioned report, pursuant to Rule 436(c) under the Securities Act
of 1933, is not considered a part of the Registration Statement prepared or certified by an
accountant or a report prepared or certified by an accountant within the meaning of Sections 7 and
11 of that Act.
/s/ Deloitte & Touche LLP
Parsippany, New Jersey
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