SAN FRANCISCO, JUNE 20 -- The next decade of the AIDS epidemic will be worse and more complex than the first, with the disease spreading among women and adolescents and into demographic pockets that are now considered "safe," according to a three-year study issued today by a branch of the National Academy of Sciences.

The report was released by the National Research Council on the opening day of the Sixth International AIDS Conference, which was also marked by the arrest outside the building of about 90 demonstrators protesting U.S. immigration policies toward AIDS victims.

The report states in blunt terms that, contrary to recent reports that suggest the AIDS epidemic may have peaked, its "dimensions are sizable and will continue to grow" for years.

"We can find little credible evidence that the end of the AIDS epidemic is in sight," said Don C. Des Jarlais, vice chairman of the committee and an expert on AIDS among drug abusers. "We believe the picture of AIDS and HIV infection in the foreseeable future is one of a continuing toll of sickness and death for a steadily broadening profile of individuals."

For adolescents, the forecast was especially troubling. Studies of recruits for military service show that in most cities rates of infection have become equal among 17- and 18-year-old men and women. In the past, nearly three times as many men were infected as women.

The report cites a variety of statistics and surveys for its conclusions, including the rise in numbers of infected women who are sexual partners of intravenous drug users and the rise of infections among users of crack cocaine and alcohol. Although neither crack nor alcohol transmits the AIDS virus, both are heavily associated with the type of unsafe sexual behavior that does.

The proportion of all reported AIDS cases occurring among women has grown from about 6 percent in 1982 to roughly 10 percent today, the study found. In Northeast cities the figure has risen from 8 percent in 1982 to 18 percent today. Most of those cases are among women who have themselves injected drugs, but the number stemming from sexual contact has grown as well.

In a surprising but positive finding, the researchers reported that, despite early fears, they could find no evidence that female prostitutes were transmitting AIDS cases to the larger heterosexual population in significant numbers. A large percentage of prostitutes reported using condoms, and most clients say they prefer oral sex, which is not thought likely to transmit the virus.

The panel issued a variety of recommendations that flow from one theme: Do more. They expressed particular concern that the federal government continues to devote only $200 million of its multibillion-dollar annual AIDS budget to prevention and education.

"We need to be frank and explicit," Des Jarlais said at a briefing here. "There has been a long American tradition of not talking about sex in explicit detail and there has been an American tradition of not providing adequate health care to people with substance abuse prolems. AIDS has upped the ante."

As have many other such panels, including those of the Institute of Medicine, the President's AIDS Commission and the National Commission on AIDS, the committee found a "critical need" to conduct a broad national survey of sexual behavior and to aim prevention strategies at groups that need them most. Currently, the information used to guide most decisions on who is at greatest risk comes from the sexual behavior data in the Kinsey Report, published nearly 50 years ago.