The United Steelworkers of America and the Aluminum Brick & Glass Workers International Union said they unanimously rejected a contract proposal from Aluminum Co. of America and Reynolds Metals.
The unions cited changes in health insurance sought by the companies as one problem area.
The steelworkers union said the companies wanted to make "drastic" cuts in health care coverage, with workers assuming a "substantial" part of the cost.
The unions are working under a one-year contract extension that runs out May 31, 1993.
They imposed a target deadline of Oct. 2 for an early agreement. No new talks were scheduled.
Alcoa had no immediate comment, and Reynolds officials were not available for comment.