Cancer statistic reports show that the incidence of melanoma has increased each decade. It is now estimated that approximately 5 percent of the patients with primary cutaneous melanoma will develop another primary melanoma in their lifetime. This report describes the information gathered from 27 patients at the Yale Melanoma Unit who have developed 59 individual primary melanomas; 22 of the patients developed a second primary melanoma, and 5 patients each developed three primary melanomas. In 8 patients (30 percent), the second primary melanoma was diagnosed within 1 month of the first malignancy and was considered synchronous. The remaining 24 melanomas in the 19 patients presented subsequently: 4 (17 percent) within the first year, 7 (29 percent) during the second year, and 13 (54 percent) beyond the second year of the first diagnosis. Although the thickness of the initial melanoma ranged from 0.2 to 6.0 mm, all subsequent melanomas were either in situ or less than 1.0 mm in thickness. This study shows that patients who developed more than one melanoma invariably had thin subsequent lesions. The implications of the multiple melanomas are not a poorer prognosis, but rather that the patients' prognosis is the same as that of the original, or thickest, melanoma.