Alcoa and subsidiaries EXHIBIT 15

October 27, 2005

Securities and Exchange Commission

100 F Street, NE

Washington, D.C. 20549

RE: Alcoa Inc.

Commissioners:

We are aware that our report dated October 27, 2005, on our review of interim financial information of Alcoa Inc. and its subsidiaries (Alcoa) for the three-month and nine-month periods ended September 30, 2005 and 2004 and included in Alcoa’s quarterly report on Form 10-Q for the quarter ended September 30, 2005 is incorporated by reference in its Form S-8 Registration Statements (Nos. 33-24846, 333-32516, 333-106411, 333-36214, 33-22346, 33-49109, 33-60305, 333-27903, 333-62663, 333-79575, 333-36208, 333-37740, 333-39708, 333-115717, and 333-128445) and Form S-3 Registration Statement (No. 333-74874).

Very truly yours,

/s/ PricewaterhouseCoopers LLP

Pittsburgh, Pennsylvania

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