Incidents of AIDS-related discrimination are increasing across the nation, not only against those who are ill with the disease or infected with the human immunodeficiency virus but also their relatives and care-givers, according to a study released yesterday by the American Civil Liberties Union.

The ACLU said complaints of AIDS-related discrimination increased by 50 percent in 1988 and 88 percent in 1987. In 1988, it said, such complaints rose 35 percent faster than newly diagnosed AIDS cases.

Of the incidents, 30 percent involved people who experienced discrimination "because of the perception that they were HIV-infected or because they care for a person with HIV disease," the report said.

A Connecticut family, for example, was denied housing because an adopted son had AIDS, and an Illinois employer fired a worker after learning that "someone {he} knew was HIV-positive," the report said. One incident investigated in California involved an individual "who was refused service after he informed his dentist that his brother had recently died of AIDS," the report said.

Nan B. Hunter, principal author of the report, said the study "shows how extraordinarily persistent discrimination remains in this country, even after science has proven there is no risk of casual transmission."

Most instances of discrimination occurred in employment, housing, public accommodations, insurance, delivery of government benefits such as Social Security and Medicaid, and access to health care.

The ACLU said that inconsistencies and gaps in anti-discrimination laws further contributed to the problem. State and local laws vary widely, and the two federal statutes that prohibit discrimination against the disabled are limited in their coverage.

The ACLU conducted the study by surveying legal and advocacy agencies nationwide. An estimated 40 percent of the agencies completed the ACLU's discrimination questionnaire. They reported an estimated 13,000 complaints of HIV-related discrimination between 1983 and 1988.

"The number of complaints and referrals represent what are probably the minimum figures," the report said. "Had we asked even more agencies for their experiences, no doubt we would have received even more reports of discrimination."