Twenty-seven children with non-A, non-B hepatitis were studied with regard to their clinical, serologic, and histologic features. In contrast to adult patients, non-A, non-B hepatitis developed in most pediatric patients (19 out of 27) in the absence of identifiable parenteral exposure, probably because of fewer chances for exposure of children to blood or blood-contaminated products. Perinatal transmission was considered possible in one of the patients. Fulminant hepatitis had occurred in six patients, two of whom died. It is noteworthy that fulminant hepatitis usually occurred in children with sporadic non-A, non-B hepatitis. The progression to chronic hepatitis after acute illness is less likely in children than in adults. Chronic hepatitis developed in four patients. Two of these were asymptomatic at presentation, suggesting that in some patients, non-A, non-B hepatitis infections may remain undetected and progress to chronic hepatitis. Liver histologic examination was performed in 11 patients. There were no characteristic histologic findings which could differentiate non-A, non-B from B hepatitis. Antibodies to hepatitis C virus (anti-HCV) were tested in 22 of the 27 patients and 8 (36%) were seropositive for anti-HCV.