Idiopathic neonatal hepatitis (INH) is a syndrome characterized clinically and histologically but there is little information concerning the relationship between the clinical features and histological findings. In the present study, sixty-two patients clinically diagnosed as non-familial INH were histologically classified into four groups according to a provisional definition based on predominant lesions and examination of their clinical features. Patients of cholestasis (n = 23) and giant cell hepatitis (GCH, n = 21) were most frequent (37% and 33%, respectively), and patients of fatty liver (n = 10) and hepatitis (n = 8) were less common (16% and 13%). The GCH group showed a dominance of male, low birthweight, older and breast-fed babies. The cholestasis group demonstrated a dominance of male, low birthweight, younger and bottle-fed babies. The hepatitis group had the highest frequencies of high-grade hepatomegaly and splenomegaly. Fifty six cases completely recovered. Two died of hepatic failure in early infancy and four had chronic liver diseases at the age of 12 months. The fatty liver group had the worst outcome. Histological features in non-familial INH were variable and typical giant cell hepatitis was seen in only one-third of patients. Characteristic clinical features in each histologically classified group may suggest heterogenous etiologies underlying non-familial INH.