EXHIBIT 15 July 7, 1998 Securities and Exchange Commission 450 Fifth Street, N.W. Washington, D.C. 20549 RE: Aluminum Company of America 1. Form S-8 (Registration Nos.33-24846 and 333-00033) Alcoa Savings Plan for Salaried Employees; Alcoa Fujikura Ltd. Salaried 401(k) Savings Plan 2. Form S-8 (Registration Nos.33-22346, 33-49109, 33-60305 and 333-27903) Long Term Stock Incentive Plan 3. Form S-3 (Registration No. 33-60045) and Form S-3 (Registration No. 33-64353) and Form S-3 (Registration No. 333-59381) Debt Securities and Warrants to Purchase Debt Securities, Preferred Stock and Common Stock of the Company and Trust Preferred Securities of Alcoa Trust I 4. Form S-4 (Registration No. 333-58227) Registration of Alcoa common stock, par value $1.00 per share Ladies and gentlemen: We are aware that our report dated July 7, 1998, except for Note i, for which the date is August 5, 1998, accompanying interim financial information of Aluminum Company of America (Alcoa) and subsidiaries for the six-month period ended June 30, 1998, is incorporated by reference in the registration statements referred to above. Pursuant to Rule 436 (c) under the Securities Act of 1933, this report should not be considered as part of a registration state- ment prepared or certified by us within the meaning of Sections 7 and 11 of that Act. Very truly yours, /s/ PricewaterhouseCoopers LLP PricewaterhouseCoopers LLP -27-