Temporal changes in the incidence of cutaneous malignant melanoma (CMM) were examined in the San Francisco-Oakland (California, United States) Metropolitan Statistical Area (MSA) between 1976 and 1987, using data from the population-based cancer registry. This analysis was conducted after the completion of a project designed to eliminate bias in the reporting of CMM due to changes in medical practice. The incidence of CMM is higher in the San Francisco-Oakland MSA than nationally. From 1976 through 1987, the incidence of invasive CMM increased from 9.8 +/- 0.9 to 16.5 +/- 1.1 per 100,000 (P = 0.0001) among men and from 9.3 +/- 0.8 to 12.7 +/- 0.9 per 100,000 (P = 0.001) among women. Age-specific, histologic-specific, and anatomic site-specific trends were also evaluated. The temporal patterns of CMM suggest that the recent increases are not accounted for solely by ascertainment bias due to reporting practices. The observed trends are consistent with early detection efforts and with changes in the prevalence of risk factors.