We examined the incidence of primary invasive melanoma in the municipality of Reggio Emilia, northern Italy, in the period from 1986 to 1997. We identified 169 cases, five of which were intraocular. After adjustment for confounders, the risk of having a thick melanoma (Breslow > or = 1 mm) did not decrease over time, except in older females. The age-standardized incidence of cutaneous melanoma during the entire study period was 7.57 in males and 11 in females; from 1986-1991 to 1992-1997, it rose from 5.04 to 10.04 cases/100,000 person-years in males and from 8.96 to 13.09 cases/100,000 person-years in females. In males, the increase in incidence was almost entirely confined to subjects aged 30 or more, suggesting a possible cohort effect. We noted rising age-standardized incidences over time both in males with thin tumours (Breslow < 1 mm) (from 2.05 to 4.38 cases/100,000 person-years) and thick tumours (from 2.73 to 5.51 cases/100,000 person-years), while in females the increase was limited to thin melanomas (from 3.14 to 6.93 cases/100,000 person-years), mainly due to an increase in the older age groups (50 69 years and > or =70 years). The increase in thick melanomas among males and the expected cohort effects suggests antecedent exposure to environmental risk factors.