THE RELATIONSHIP of pigmented moles and melanomas has been studied with regard to histogenesis, age of subjects, malignant derivation, etc., but the significance of their proportionate regional distribution has been largely ignored. We consider these clinical facts to be of sufficient interest and, perhaps, importance to justify the presentation of this information by four series of scattergrams showing (a) the pattern of primary melanin distribution when unaffected by sunlight or other melanin-provoking exposure; (b) the distribution of benign pigmented moles in 1,000 white adult patients; (c) the distribution of benign pigmented moles in 840 patients who, with their physicians, were so suspicious of these lesions as to have them removed for microscopical examination, and (d) the regional distribution of 1,225 verified malignant melanomas. From an outpatient diagnostic service, 1,000 adult white patients, who came for other complaints, were carefully examined in order to note and record the character, number, and