Management Advisory Agreement

Exhibit 10

TPG Genpar III, L.P.

301 Commerce Street, Suite 3300, Fort Worth, Texas 76102

Tel (817) 871-4080 - Fax (817) 871-4088

March 24, 2005

MEMC Electronic Materials, Inc.

501 Pearl Drive

St. Peters, MO 63376

Attention: David L. Fleisher

Dear David:

Reference is made to the Management Advisory Agreement (the “Agreement”) dated as of November 13, 2001, by and between MEMC Electronic Materials, Inc. (the “Company”) and TPG GenPar III, L.P. (“TPG”). Capitalized terms used herein without definition shall have the meanings ascribed to them in the Agreement.

This letter agreement reflects the agreement of TPG and the Company with respect to terminating the Agreement.

For good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the Company and TPG hereby agree that, effective as of December 31, 2004, the Agreement is hereby terminated and neither the Company nor TPG shall have any further ri