A group of 79 patients with histologically proven malignant melanoma was compared with an agesex matched, cancer-free, control group for certain phenotypic characteristics, environmental influence (outdoor exposure) and genetic cancerproneness. Statistical analysis of the data shows that there is a tendency for patients with malignant melanoma to have light complexions, light eyes, blond or red hair, and to spend a greater amount of time outdoors, when compared with the control group. There is close correlation of findings in these respects with our previously reported study of patients with basal-cell epithelioma.