Thirty male Wistar rats were fed with 15% ethanol (V/V) for one year. Thirty other male animals were the control group. To determine the possible metabolic disturbances caused by chronic ethanol feeding in blood we measured in blood metabolic parameters, and in a liver perfusion assay the hepatic insulin clearance and hepatic urea production in these animals. Between the ethanol-fed and the control animals there were significant differences in the following parameters: blood insulin concentration (47 vs. 2 microU/ml) and activities of amino acid transferases in liver homogenates at the end of the perfusion experiments (ASAT, 5950 vs. 70; ALAT, 3632 vs. 93 U/l). The other parameters were still normal in the ethanol-fed animals. Thus in these experiments after 12 months of 15% (V/V) ethanol feeding the rats still showed only a state of beginning metabolic disturbances in the liver. The results are discussed under consideration of the formation of acetaldehyde protein adducts in all rat organs investigated, namely, liver, kidney, heart and skeleton muscle, gut and spleen.