August 14, 2007

Mr. Matthew A. Ouimet
President – Hotel Group
Starwood Hotels and Resorts Worldwide, Inc.
1111 Westchester Avenue
White Plains, NY 10604

Dear Matt,

This letter supplements the agreement, dated September 21, 2006, between
Starwood Hotels & Resorts Worldwide, Inc. (the “Company”) and you that sets
forth the terms of your employment with the Company (the “Employment
Agreement”).

As previously announced, the Company has commenced a search for a new Chief
Executive Officer (“CEO”). The new CEO is expected to be hired in 2007. The
Company desires to offer you special severance benefits in the event your
employment is terminated after the CEO is hired. In the event that, after the
new CEO is hired, the Company terminates your employment for any reason other
than “cause” or you terminate your employment for “good reason” (as such terms
are defined in the Employment Agreement), in addition to the payments and
benefits provided in such circumstances under the Employment Agreement, 50% of
the stock options (determined on a tranche by tranche basis) and 50% of the
restricted stock that have been granted to you under any of the Company’s
benefit plans and which remain unvested on the date of termination shall become
vested and exercisable as of the date of termination. The special severance
benefit will expire on the second anniversary of the date the new CEO commences
employment with the Company.

Except as modified by this letter, the Employment Agreement remains in full
force and effect.

By signing and returning this letter, you confirm that this letter accurately
sets forth the understanding between you and the Company and that you accept and
agree to the terms as set forth above.

Very truly yours,

Kenneth S. Siegel

Chief Administrative Officer & General Counsel

Accepted and Agreed:

     
Matthew A. Ouimet