All 9 cases of ring chromosome 7 syndrome already identified had skin lesions: 7 had vascular lesions, 5 showed large pigmented congenital nevi, 3 had café-au-lait spots and in 1 case there were achromic spots on the trunk. One girl developed malignant melanoma at the age of 17 years. It appears that in patients presenting with growth retardation and pigmented skin lesions, with or without mental retardation, a cytogenetic study is indicated to search for ring chromosome 7, which is probably more frequent than suggested by the literature.