The cause of hyperpigmentation usually is traced to the activity and presence of melanocytes. Café au lait macules may be solitary benign findings or may indicate the presence of neurofibromatosis with its associated complications. Diffuse hyperpigmentation should prompt a search for offending medications or systemic diseases such as hemochromatosis, hyperthyroidism, and Addison's disease. In these instances, the hyperpigmentation may be ameliorated by discontinuing offending medications, performing serial phlebotomy in patients with hemochromatosis, instituting cause-specific treatments in patients with hyperthyroidism, and replacing deficient glucocorticoids and mineralocorticoids in patients with Addison's disease. Cosmetic treatment with bleaching agents or lasers can be used to decrease pigmentation of ephelides (freckles) and lentigines.