As the nation moves into the second decade of the epidemic, AIDS advocates say that patterns of discrimination also appear to be changing as more subtle prejudices involving denial of basic health care replace overt forms of bias.

To be sure, advances in the laboratory have been matched by progress in the courts, state legislatures and Congress. The landmark Americans With Disabilities Act -- which has passed both houses of Congress but must be resolved by conference committee and signed by President Bush -- will extend protection to people with AIDS. And as Bush said earlier this year in his first speech about AIDS: "Once disease strikes, we don't blame those who are suffering . . . We try to love them and care for them and comfort them. We don't fire them, we don't evict them, we don't cancel their insurance."

Yet beneath this understanding and support for people with AIDS lie more stubborn and pervasive forms of discrimination. While all states have laws against discrimination, and more than half have extended them specifically to cover AIDS, actual protection varies from state to state, according to a report last year by the George Washington University AIDS Policy Center.

And in a new study on AIDS discrimination released earlier this week, the American Civil Liberties Union AIDS Project concluded that discrimination cases are still on the rise, although the rate of new cases is slowing.

In a survey of 260 government and volunteer agencies from every state, the ACLU found 13,000 formal AIDS discrimination complaints had been filed between 1983 and 1988. In 1987, the number of all complaints rose 87 percent; in 1988, there was a 50 percent increase -- in fact, the number of discrimination reports rose 35 percent faster than the actual number of newly diagnosed AIDS cases.

What's more, many instances of AIDS discrimination are probably not reported, said Nan D. Hunter, director of the ACLU study. Hunter noted that only 149 discrimination cases of 13,000 complaints went to court since the beginning of the epidemic -- a ratio of 1 in 87.

One reason is that many problems are handled by state or local anti-discrimination agencies. "We are able to resolve 85 percent of the complaints within a month without having to file a formal complaint," said Keith O'Connor, director of the New York City Commission on Human Rights' AIDS Discrimination Unit, which handles about 600 complaints a year. But if a quick solution is not possible, it can take four to seven months to close a case. "You want to do things much more quickly for people with AIDS," he said, because many patients die within two years of diagnosis.

Few AIDS discrimination cases have been filed with the D.C. Department of Human Rights, according to associate director James Mercer. There were only two cases reported in 1987, five in 1988, 10 in 1989 and 12 so far this year. All were men.

"I think that there is a lot more discrimination on the basis of AIDS than is actually being reported to us," Mercer said. "I don't think that we have a good gauge of the severity of the problem in the District."

When the epidemic first began, there was a high degree of panic in many communities because doctors didn't know what caused it or how it spread. Funeral home directors in New York City refused to handle the bodies of those who died from the disease. In Westchester County, N.Y., a blind woman and her two children were evicted from public housing because she had AIDS.

More than 30 states have passed laws that protect the confidentiality of people with AIDS, according to the GW study. "It is impossible to talk about confidentiality and discrimination separately," said Kate Cauley of the GW AIDS Policy Center. "As soon as a person's HIV status is known, they are open to discrimination on every level, personal to professional."

The stigma of having AIDS remains so strong that one third of the AIDS discrimination complaints included in the ACLU study were filed by people who didn't have the disease: they were discriminated against because they were only thought to be infected, believed to have a high-risk life style or cared for people with AIDS. In Texas, for example, the ACLU fought -- and lost -- a case in which a woman was fired after her employer discovered that she volunteered in an AIDS service agency.

"In the early days, there was not much pretense. If you had AIDS, you were fired," said Mitchell Netburn, director of the New York State Division of Human Rights' Office of AIDS Discrimination Issues. The Reagan Justice Department initially said such discrimination was legal, though later rescinded the opinion.

Now, most large companies understand that it is illegal to discriminate against people with AIDS and have policies to prevent it, Netburn said. But, he added, such discrimination still occurs in smaller firms.

The most surprising new source of discrimination occurs in doctors' or dentists' offices. "We have had an explosion of that," Netburn said. "That was 19 percent of all our cases in 1989."

Increasingly, health care workers, fearing infection, are refusing to treat AIDS patients. Some claim they lack the expertise or the training to maintain sterile conditions for infected patients.

In one case, New York State has accused Daniel Elstein, an orthopedist in Syracuse, of AIDS discrimination. Elstein had been treating a gay man for orthopedic problems for several years, but, according to Netburn, when he discovered the man had AIDS, he discontinued treatment even though no invasive procedures were involved.

In an interview, Elstein's lawyer said that the man had asked him to treat his AIDS-related problems. Elstein said he declined because he is not an AIDS expert and referred the man, who has since died of his disease, to a specialist.

The case is considered a test of the right of doctors and dentists to refuse to treat AIDS patients. Elstein and several physician groups that have filed "friend of the court" briefs in support of his case contend that doctors' offices are not "places of public accommodation," such as restaurants or stores, which by law must serve all customers. The state Human Rights Commission is planning a hearing on the case later this summer.

In addition, according to lawyers and officials with government anti-discrimination offices, a significant number of hospitals, nursing homes, and even hospices and abortion clinics have turned away AIDS patients.

Some state laws and policies promulgated by the Centers for Disease Control and the American Medical Association say that medical personnel must treat AIDS patients.

The ACLU report predicts that the cost of the growing number of AIDS patients will make medical care and insurance discrimination worse. "By 1992, insurers, employers, health care providers and others may increasingly attempt to cut costs through discrimination," the report said.

Meanwhile, the virus continues to spread from Fire Island and Castro Street to Newark and the barrios of Los Angeles; it now attacks poor, minority residents, many of whom are politically powerless.

"If you get a poor, black, intravenous drug abuser who is HIV infected, and he seeks treatment but doesn't get it, is he being discriminated against because he is black, poor or has HIV?" asked Lawrence O. Gostin, executive director of the American Society of Law and Medicine in Boston. "Any way you slice it, he is not going to get the care."

The ACLU found that minorities file few AIDS discrimination complaints. Though blacks and Hispanics make up 40 percent of those with AIDS, only 23 percent of the complaints were filed by minorities.