A total of 105 cases of fulminant hepatitis sen during the period fom January 1979 to December 1983 and filed by the pediatric services of major hospitals throughout Japan with the diagnostic criteria set by the 12th Inuyama Liver Symposium were analyzed. The male:Female atio was 2:1. Fifty-six per cent of he cases werre younge than 2 years and 29.5% were thought to be due to hepaitis B infection. The majority of B-type fulminant heptitis cases younger than 6 months not related to blood transfusion had been born to HBeAg-negative caie mohers. The overall ftality was 85.7% and there was no difference betwen the acutte and subacute varieties of fulminant hepatic failure.