Many studies have characterized the phenotypic features of individuals who are likely to develop cutaneous melanoma. One of the major items included in melanoma risk assessment has been the presence of clinically atypical nevi (dysplastic nevi). This study assessed the number of subjects with dysplastic nevi in groups of patients with uveal melanoma or cutaneous melanoma and in a group of volunteer controls. The SPSS program was used to calculate the odds ratios (hereafter called relative risks; RR) and 95% confidence intervals (C) in melanoma patients and controls. The RR was 4.36 for uveal melanoma (95% Cl 1.84-10.36) and 4.22 for cutaneous melanoma (95% Cl 1.81-9.84). These results suggest that cutaneous dysplastic nevi are a significant risk factor for uveal melanoma.