This study describes the mental health of a large cohort of gay men participating in the Chicago Multicenter AIDS Cohort Study/Coping and Change Study. Six biannual questionnaires were self-administered between 1984 and 1988. General mental health was determined by the Hopkins Symptom Checklist (HSCL). An abbreviated version of the Center for Epidemiologic Study Depression Scale (CESD-5) and an adapted Diagnostic Interview Schedule (DIS) question also measured depression. Suicidal ideation was assessed by one question in the HSCL. AIDS-specific distress was determined by three subscales specifically developed for this study. While mean HSCL and CESD-5 scores were stable during the observational period, AIDS-specific distress increased over time. The HSCL scores for the cohort were somewhat elevated above general population norms but considerably below psychiatric outpatient norms. Fewer than 12% of the men reported elevated HSCL or CESD-5 scores three or more times. A self-reported episode of depression of two weeks or more, measured by the DIS screening question, was experienced by 40.1% of the sample. Suicidal ideation was reported on three or more visits by 18.8% of the men. The younger members of this cohort exhibit greater general and AIDS-specific distress. Income was inversely associated with general distress. HIV-seropositive participants had generally higher AIDS-specific distress scores than those who were seronegative, but their scores were equivalent on the HSCL and CESD-5.