Mandatory blood tests of U.S. military recruits show that blacks test positive for exposure to the AIDS virus at a rate four times as high as whites, public health experts said here yesterday at a national conference on AIDS and blacks.

Experts cited Defense Department figures as new evidence that acquired immune deficiency syndrome has joined a list of other diseases, including cancer, tuberculosis and hypertension, that disproportionately affect blacks in this country.

"Black men are at high risk for everything and AIDS is no exception," said Henry Chinn, founder of the Black Men's Association of Boston.

The military figures, released this month by the Walter Reed Army Institute of Research, are the result of blood tests of 308,076 recruits conducted from October of last year through May.

Among the 237,586 whites tested, the rate of exposure to the virus was 0.9 per 1,000 recruits; among the 55,185 blacks, the rate was 3.9 per 1,000. The rate of positive tests for the 15,305 recruits of other racial groups was 2.6 per 1,000.

The results show that blacks test positive for the AIDS virus at a higher rate, but that white males still account for the majority -- 60 percent -- of those who have already developed the disease. Blacks account for 25 percent of the nearly 23,000 cases of AIDS in the United States, according to federal figures.

Public health experts frequently use the results of military recruit testing as indicators of certain aspects of health, but note that comparisons cannot be made with the general population.

AIDS exposure among those donating blood to the Red Cross, for example, is four cases per 10,000 donors, compared with 15 cases per 10,000 military recruits of all races, said Walter Dowdle, AIDS coordinator for the U.S. Public Health Service.

However, the military population would be expected to have more cases because most recruits are young males, according to recent congressional testimony of Dr. William E. Mayer, assistant secretary of defense for health affairs.

Males account for 92 percent of all U.S. AIDS cases, according to the federal Centers for Disease Control.

Experts at the conference at the Washington Convention Center theorized that there may be a greater incidence of bisexuality and drug use that could account for the larger rate of black recruits testing positive for exposure to AIDS.

"There are major problems with blacks and IV intraveneous drug abuse and AIDS nationwide," said Dr. Wayne Greaves, chief of infectious diseases at Howard University Hospital. "Black women account for 52 percent of all female cases of AIDS. With the 270 children with AIDS, 60 percent are black. With blacks representing only 12 percent of the U.S. population, these are serious numbers."

Representatives of the National Coalition of Black Lesbians and Gays, which organized the conference, also met yesterday with Surgeon General C. Everett Koop to discuss ways of devoting more federal attention to the problem of AIDS among nonwhites.

Mayor Marion Barry told the 600 health professionals and gay activists attending the conference, "There are some views and some discussion that AIDS is a white male problem. We know differently."

The D.C. government spent $45,000 in 1984 on activities to fight AIDS. Barry said his administration was "stepping up" its efforts and has budgeted more than $2 million for AIDS education, prevention and support of AIDS patients in the coming year.

The city awarded a $92,874 contract this month to Koba Associates Inc., a private, minority-owned firm, to complete a three-month project to educate blacks and Hispanics about AIDS prevention. "This is the single biggest public health problem that we're facing," said Dr. Andrew McBride, the D.C. public health commissioner.

In the spring, McBride was forced personally to lift the body of a deceased AIDS patient after city crews refused to move him. McBride said that since the incident, the D.C. police training center has produced a video on AIDS that is shown to employes of the medical examiner's office, police, fire and other rescue personnel.

Several speakers at the conference said black males have more difficulty acknowledging they are homosexual than do white men, and that this affects efforts at reaching black men who are at risk.

Black men "are hiding the sexuality issue and saying they got infected by drugs," said Julius Johnson, a San Francisco psychologist who has studied the issue.

Chinn noted that many black women may be at risk unknowingly because few black men who engage in sex with men admit it openly. "With most black men, bisexuality is something that they do, it's not a life style."

Representatives of several gay men's groups across the country said they have organized gatherings in homes to pass out literature on how to have sex without becoming exposed to AIDS and to provide information on the disease in informal settings, often with music and refreshments.

"Clearly the information is not getting out in any other mechanism," said Tim Offutt, a member of the Kupona Network in Chicago, a black outreach group on AIDS. Ernest Andrews, a counselor with the Pacific Center AIDS Project in Oakland, said such parties are one of the few ways of reaching the young and runaways.