Reticulate acropigmentation (RA) comprises dyschromic disorders that generally have an autosomal dominant pattern of inheritance, Two main forms of RA have been described: reticulate acropigmentation of Kitamura (RAK) and reticulate acropigmentation of Dohi (RAD). We observed a 21-year-old white woman who had progressive reticulate hyper- and hypopigmentation on the volar surface of her forearms and the dorsa of her hands. Many of her relatives have similar lesions. There were no pits or breaks in the epidermal ridge pattern on the palms. A biopsy specimen revealed areas with an excess of melanin in the basal layer alternating with others in which melanin was totally absent, Electron microscopic findings in a hypermelanotic area showed an increased number of melanocytes with high metabolic activity. In the hypomelanotic areas the melanocytes were morphologically abnormal with melanosomes at the early stages of development. (J Am Acad Dermatol 1997;37:884-6.)