Population-based disease registries for acquired immunodeficiency syndrome (AIDS) and cancer were linked for San Francisco residents to study the pattern of AIDS-associated malignancies diagnosed during the time period 1980–1987. A total of 1,756 newly diagnosed malignancies were identified during these years among members of the AIDS cohort. Of these, 1,752 (99.7%) occurred in males, 1,454 (83%) were Kaposi's sarcoma, 235 (13%) were non-Hodgkin's lymphoma, and 16 (1%) were Hodgkin's disease. The distributions of AIDS patients with cancer differed significantly from those without cancer by race and by risk group. Malignancies known to be human immunodeficiency virus (HIV)-associated, and now diagnostic of AIDS (Kaposi's sarcoma, non-Hodgkin's lymphoma), were, as would be expected, dramatically in excess among AIDS patients. Some malignancies not traditionally thought to be HIV-associated appear to have occurred more often than expected in the study cohort. These include Hodgkin's disease, rare non-melanoma skin cancers, and cancers of the rectum, anus, and nasal cavity. Malignancies known to be HIV-associated were more likely to be diagnosed concurrent with or subsequent to first AIDS diagnosis. Conversely, malignancies not known to be HIV-associated were more likely to be diagnosed before AIDS diagnosis. Compared with the concurrent reference population of the San Francisco Bay Area, there was little or no increase in Kaposi's sarcoma over the time interval of this study. For non-Hodgkin's lymphoma, and suggestively for Hodgkin's disease, however, the temporal increase has been quite dramatic.