Sarcoidosis is a systemic granulomatous disorder of unknown etiology. While recognized as a distinct clinical entity for over a century, information on incidence, prevalence, risk factors, and natural history in the United States remains quite limited. Data available on the occurrence in the United States indicate that the incidence ranges from about 1 to 10 per 100,000 and prevalence from about 5 to 50 per 100,000. Incidence appears highest for young adults, ages 25 to 40, higher in females than males, and much greater in African Americans than other ethnic groups. Morbidity from this chronic disease is not well estimated by mortality data. In 1981, there were over 10,000 discharges from United States hospitals for sarcoidosis. Like mortality data, the hospital discharge information probably substantially underestimates the morbidity associated with sarcoidosis which is typically managed on an outpatient basis.