The incidence of Kaposi's sarcoma (KS) in 1976-90 was assessed in Italy, taking advantage of a network of nine population-based cancer registries covering, at its maximum, approximately 5.6 million subjects. The first examined period (1976-84) substantially reflects the epidemiology of KS prior to the AIDS epidemic in the registration areas. Elevated incidence rates, standardised to the Italian population of 1981, of 1.05/100,000 men and 0.27/100,000 women emerged in 1976-84 (ie from two-to threefold higher than in the USA and Sweden, more than tenfold higher than in England and Wales). These high rates, especially remarkable in the Registry from the south of Italy (ie Ragusa, 3.01/100,000 men and 0.54/100,000 women) suggest that the prevalence of the still unknown causative agent for KS was high, at least in some parts of Italy, prior to the AIDS epidemic. In the most recent period (1985-90), an approximately twofold increase in KS incidence rates in Italian men below age 50 was observed (from 0.15 in 1976-84 to 0.47 in 1985-90). Conversely, declines in KS incidence were recorded in older men.