Two groups, 16 nonalcoholic steatohepatitis patients (group I) and 22 alcoholic hepatitis patients (group II) classified according to the presence or absence of drinking and their histological characteristics, were compared on the basis of clinical, biochemical, and liver biopsy findings. The frequencies of female patients (p less than 0.01), obesity (p less than 0.001), and maturity-onset diabetes (p less than 0.005) were significantly greater in group I than in group II. The serum glutamic pyruvic transminase (p less than 0.05) and gamma-glutamyltranspeptidase (p less than 0.05) contents were significantly greater in group II than in group I. The cholinesterase content (p less than 0.05) was significantly less in group II. Significant differences were found in the grades of nuclear vacuolation (p less than 0.001, Fisher's exact probability test), periportal pericellular fibrosis, proliferation of bile ductules, and changes in the shape of the portal tracts (p less than 0.001, Wilcoxon's rank-sum test). Zonal necrosis in group I was seen in only severe steatohepatitis. These clinical and biochemical findings were found to be useful in differentiating nonalcoholic steatohepatitis from alcoholic hepatitis. Liver biopsy was of limited value at best in separating the two conditions.