Persons with human immunodeficiency virus/AIDS are at high risk of Kaposi's sarcoma (KS), non-Hodgkin lymphoma (NHL), and possibly anal cancers. To examine whether this risk preceded the AIDS epidemic, we used pre-AIDS era data from the Surveillance, Epidemiology, and End Results program (excluding Connecticut) from 1973 to 1976, and the Connecticut Tumor Registry from 1940 to 1976. We compared risk of being single (a surrogate to identify men who might be homosexual) to those ever married, using a case control matching study with up to 10 controls per case. Overall, no excess risk was observed for KS (risk ratio for men 20-59 years old: 1.00; 95% confidence interval 0.218-3.61), but there was a suggestion of higher risk (4.00; 0.54-29.48) in 1973-1976, the period just before the AIDS epidemic. The NHL risk (0.85; 0.74-0.99) was slightly low, but for anal cancer the risk ratio of being single was significantly high both in men 20-59 years old (5.68) and older men (2.78) long before the AIDS epidemic. If the excess risk was solely due to being homosexual, the actual relative risk in the subset who were homosexual must have been much higher, given that only a fraction of the single men would have been homosexual. As comparison groups to verify the methodology, we used colon (no association with marital status) and prostatic cancer (decreased in single men), with findings as reported in other studies. Thus, single men may have been at an excess risk of KS (but a slightly low risk of NHL) just before the AIDS epidemic and have been at excess risk of anal cancer for many years before the AIDS epidemic.