The effects of ethanol and hepatic vitamin A on lipocyte proliferation were studied in regenerating rat livers. Positive identification of proliferating lipocytes was achieved by a double immunostaining sequence for cytoplasmic desmin and bromodeoxyuridine-labelled nuclei. Ethanol administration caused a 76 and 36% reduction in labelling indices of lipocytes 2 and 3 days after hepatectomy, respectively, thereby delaying the onset of the proliferative peak of lipocytes by 1 day compared to the control. Hepatic vitamin A did not decrease until 4 days after hepatectomy. The relationship between hepatic vitamin A and lipocyte proliferation was further evaluated in rats fed diets containing four different amounts of vitamin A. Despite the striking differences in liver vitamin A levels, the proliferative activity of lipocytes was unaffected, as measured at the peak of lipocyte proliferation 2 days after hepatectomy. These data indicate that ethanol ingestion suppresses the proliferative response of lipocytes to partial hepatectomy but that this ethanol effect is independent of changes of vitamin A levels in the liver.