To examine the effect of HIV status, symptomatology and CD4+ lymphocyte level on health-related quality of life, the Medical Outcomes Study Short-Form Health Survey (SF-36) was administered to 2,295 gay men enrolled in the Multicenter AIDS Cohort Study (MACS) in 1994. Distinct physical and mental health factors of the SF-36 were found. Seropositive asymptomatic individuals and seropositive individuals with CD4+ lymphocytes > or = 500/mm3 scored as well as seronegative participants on all of the mental health domain scales, but lower on the general health perceptions and physical health composite score. Seropositive individuals with at least one symptom or with CD4+ lymphocytes below 200/mm3 scored significantly lower on all of the SF-36 scales and summary scores than seronegative controls. The SF-36 was found to exhibit similar mental and physical health factors for an adult gay male population to that previously seen in general population samples and in patient groups with other diseases. In conclusion, HIV-positive men who are asymptomatic or have CD4+ lymphocytes above 500/mm3 have similar perceived mental health but worse perceived physical health than seronegative men. HIV-positive men who are symptomatic or have CD4+ lymphocytes below 200/mm3 have worse perceived mental and physical health than seronegative men.