The ultrastructure of tissue pigmented through prolonged use of mercury-containing cosmetic creams was studied. Mercury was identified in the tissue by the technique of neutron-activation analysis. Metallic granules were observed electron microscopically in dermal macrophages, in association with elastic fibers, and lying free in the dermis. Melanin pigmentation increased secondary to the presence of the heavy metal. Vacuolated dendritic cells were observed at the dermoepidermal junction.