Liver biopsies from nine patients with maturity-onset diabetes and fatty liver hepatitis were semiquantitatively assessed, and the findings compared with those in alcoholic hepatitis. Overall appearances were similar, but the lesion in some diabetics was periportal rather than perivenular in location, and nuclear vacuolation of hepatocyte nuclei was always present. The inflammatory infiltrate often included neutrophil leucocytes, as in the alcoholic. In three patients with multiple biopsies, progression appeared to be slow, but one patient developed cirrhosis.