The Harvard-affiliated New England Deaconess Hospital recently participated in a study of 400 healthy homosexual men in Boston that suggests the presence of Acquired Immune Deficiency Syndrome (AIDS) in about one out of five of those tested.

The study, which measured the percentage of subjects who showed evidence of antibodies to the AIDS virus in their blood, is the first to appraise the seriousness of AIDS Boston.

Similar studies show that one-third of New York homosexuals tested had antibodies for the AIDS virus, with the figure ranging between 40 and 75 percent in San Francisco.

Dr. Jerome E. Groopman of the Deaconess Hospital said in an interview this week that the sample was not random, but included men who are "more sexually active individuals with a high level of anxiety about AIDS.

Although the sample was not selected randomly and does not approach the size of the Boston say population, which is estimated to be about 19,000 Groopman said it likely reflects the true degree of infection in Boston.

If the results of the study are correct, about 240 men who are already exposed to the virus will develop AIDS in Boston this year. The city has recorded 147 cases of AIDS since 1981. Ninety of these lived in Boston itself when diagnosed.