This paper reviews current knowledge of childhood sarcoidosis with regard to the epidemiology in Danes, clinical presentation, diagnostic procedures, treatment and prognosis. Sarcoidosis is a granulomatous disease of unknown aetiology, with multiorgan involvement. The diagnosis is confirmed by the demonstration of epitheloid cell granulomas in tissue biopsy specimens. During the period 1980-92, three cases of childhood sarcoidosis were recorded in Copenhagen County, which has a total population of 610,000. The approximate incidence of clinically recognized sarcoidosis in Danish children younger than 15 y of age was 0.22-0.27/100,000 children per year, corresponding to approximately three new cases in Denmark each year. The true incidence is unknown, since the disease is often asymptomatic and resolves without a clinical diagnosis being made. In children younger than 5 y of age, the disease is characterized by involvement of skin, eyes and joints, whereas in older children involvement of lungs, lymph nodes and eyes predominate. The mainstay of treatment consists of oral corticosteroids. The risk/benefit ratio of using long-term corticosteroids needs to be evaluated in each individual patient. Some patients may benefit from additional therapy with methotrexate. The long-term prognosis is not well established, but it seems to be poorer in children younger than 5 y. Older children appear to have as favourable a prognosis as young adults.