Tattoo* is a localized pigmented area caused by implantation of foreign material into skin or oral mucosa. Oral tattoos are usually caused by amalgam particles or graphite in lead pencils. A tattoo is localized, dark gray to black, non-tender, and either macular or slightly thickened. A tattoo sometimes increases in size due to ingestion of the foreign material by phagocytes and then migration of these cells. Some tattoos can be visualized on a radiograph, but absence of radiographic evidence of amalgam particles does not exclude the diagnosis of tattoo. Obviously, some tattoos are intentional artistic endeavors and do not cause a diagnostic challenge. The typical small, localized, non-thickened tattoo does not require treatment, once a diagnosis is made. A tattoo that is thickened and does not have amalgam particles evident on a radiograph should be biopsied so that nevus and melanoma can be excluded.