Temporal changes in the lifetime occurrence of opportunistic infections and malignancies among 1115 homosexual men diagnosed with AIDS were examined. Information from the AIDS surveillance registry, hospital pathology and microbiology logs, patient chart reviews, cancer registries, and death certificates was used to calculate the frequency of specific opportunistic infections and malignancies as lifetime (initial or subsequent) diagnoses. The most common lifetime diagnoses were Pneumocystis carinii pneumonia (PCP; 66.5%), Kaposi's sarcoma (KS; 50.7%), disseminated Mycobacterium avium complex (DMAC) infection (29.6%), and cytomegalovirus (CMV) infection (19.6%). From 1981 to 1990, there was a significant decrease in the rate of KS (P = .003) and a significant increase in the rate of DMAC infection (P = .03). PCP decreased during 1985-1990 (P = .009), while CMV infection increased from 1987 through 1990 (P = .03). Thus, KS and PCP have declined over time, while DMAC and CMV are causing substantial and increasing morbidity among AIDS patients.