The effect of ethanol ingestion on the uptake of labeled amino acids was studied in the in situ autoperfused dog liver. Ethanol was administered orally, as a 15 % water solution, in a dose of 4 g/kg body weight/day as the only source of water for 2 days. Amino acid uptake was measured in anesthetized dogs by means of the single-passage, multiple-tracer dilution technique. In control animals, hepatic uptake of 14C-glycine, 3H-α-aminoisobutyric acid (3H-AIB) and 3H-L-leucine were 50, 15 and 66%, respectively. In the ethanol-treated dogs, glycine and AIB uptake was reduced by 70 and 63 %, respectively. L-leucine uptake was reduced by only 23%. The plasma concentration of the naturally occurring amino acids was significantly increased after ethanol treatment, probably due to a reduced influx into hepatocytes. Simultaneous measurements of hemodynamic parameters showed a significant increase in the portal vein pressure of ethanol-treated animals, whereas the portal vein blood flow and hepatic extracellular volume were unaffected