SYNOPSIS Current concepts of melanin pigmentation in mammals, with special reference to man are explored centering on the notion that the multicellular epidermal melanin unit, rather than the melanocyte alone, serves as the focal point for melanin metabolism within rmmmalian epidermis The structural and functional organization of epidermal melanin units is described with particular attention to the intrinsic and extrinsic mechanisms which regulate their activities The significance of the epidermal melanin unit concept in the description and interpretation of skin color variations in man is evaluated in the light of new information