We studied the clinical and histopathologic characteristics of melanotic macules of the penis and vulva. The 10 lesions studied were relatively large (up to 2 cm), multifocal, irregular in outline; and had variegated pigmentation. Most were regarded as clinically atypical in appearance. Histologic examination of the lesions showed basal layer hyperpigmentation, slight melanocytic hyperplasia, epithelial hyperplasia, and stromal melanophages. No cytologic atypia of melanocytes was detectable. Information is insufficient at present to predict the natural history of genital lentiginosis or its relation to mucocutaneous melanoma.