EXHIBIT 15 August 6, 2004 Securities and Exchange Commission 450 Fifth Street, N.W. Washington, D.C. 20549 Commissioners: We are aware that our report dated August 6, 2004 on our review of interim financial information of W. R. Grace & Co. (the "Company") for the three and six month periods ended June 30, 2004 and June 30, 2003 and included in the Company's Quarterly Report on Form 10-Q for the quarter ended June 30, 2004 is incorporated by reference in its Registration Statements on Forms S-8 (Nos. 333-37024, 333-49083, 333-49507, 333-49509, 333-49511, 333-49513, 333-49515, 333-49517, 333-49703 and 333-49705). Very truly yours, /s/PricewaterhouseCoopers LLP PricewaterhouseCoopers LLP McLean, Virginia