The dyschromatoses are a group of pigmentary disorders characterized clinically by mixed and often guttate hypopigmentend and hyperpigmented lesions. There are many conditions that present with dyschromatosis, including genodermatoses, inflammatory skin diseases, infections, drug and chemical use, and nutritional disorders. Some conditions have extracutaneous features. In this article, we describe the dyschromatoses with typical onset in adulthood. Most diseases in this group are acquired conditions. To organize the various acquired dyschromatoses, we have categorized them into those with a history of chemical exposure, drug exposure or dermatological procedures, and those without a history of such exposure. In contrast to the genetic dyschromatoses, some acquired dyschromatoses are preventable and treatable. We hope this review will serve as a guide for dermatologists to the recognition and treatment of these conditions.