Annual incidence rates for 1975-1985 were derived for Kaposi's sarcoma, non-Hodgkin's lymphomas, and seven other malignancies. Never-married men in the San Francisco Bay area constituted the study population. The pattern of increase in incidence of non-Hodgkin's lymphoma among men aged 25-44 years was similar to that seen for Kaposi's sarcoma; both increased significantly in San Francisco between 1980 and 1985 (p less than 0.001), with an increase among census tracts with high incidence of acquired immunodeficiency syndrome (AIDS) that was greater than the increase seen in other San Francisco census tracts. Among men in tracts with a high incidence of AIDS, non-Hodgkin's lymphoma reached an incidence in 1985 that was five times greater than preepidemic rates. These increased rates support the conclusion of clinical studies that non-Hodgkin's lymphoma is an additional manifestation of AIDS. Similar increases in incidence rates were not observed for other malignancies, suggesting that reports of these malignancies in homosexuals may be isolated incidents. Whether rates of non-Hodgkin's lymphoma will continue to increase and whether rates of other potentially AIDS-associated malignancies will increase in the future may depend on the latency of these malignancies and the survival period of AIDS patients.