''Decisions made nearly two decades ago were based on the best scientific information of the time and were consistent with the regulations in place,'' the statement said.

The medicine, called Factor VIII concentrate, essentially provides the missing ingredient without which hemophiliacs' blood cannot clot. By injecting themselves with it, hemophiliacs can stop bleeding or prevent bleeds from starting; some use it as many as three times a week. It has helped hemophiliacs lead normal lives.

But in the early years of the AIDS epidemic, it became a killer. The medicine was made using pools of plasma from 10,000 or more donors, and since there was still no screening test for the AIDS virus, it carried a high risk of passing along the disease; even a tiny number of H.I.V.-positive donors could contaminate an entire pool.

In the United States, AIDS was passed on to thousands of hemophiliacs, many of whom died, in one of the worst drug-related medical disasters in history. While admitting no wrongdoing, Bayer and three other companies that made the concentrate have paid hemophiliacs about $600 million to settle more than 15 years of lawsuits accusing them of making a dangerous product.

The Cutter documents -- a few of them have surfaced in recent years in television and newspaper reports about Cutter's marketing practices -- were gleaned from that litigation. But because the documents did not relate directly to the suits, most went uninvestigated.

The documents -- internal memorandums, minutes of company marketing meetings and telexes to foreign distributors -- reveal and chronicle Cutter's decision to keep exporting the older product after it began making the new one, which was heat-treated to kill H.I.V. The heat treatment rendered the virus ''undetectable'' in the product, according to a government study. (There are few available records documenting the actions and decisions of the three other American-based companies that also sold unheated concentrate after offering a heated product.)

Doctors and patients contacted overseas said they had not known of the contents of the Cutter documents. Bayer and other blood-product companies, though admitting no wrongdoing, have already made some payments to foreign hemophiliacs. It is unclear if Bayer could now face legal liability specifically for selling the older product after a safer one was available.