The effect of acute ethanol administration on the hepatic metabolism of glutathione was studied in male Wistar rats. Animals fasted for 18 hr received ethanol (5 g/kg body wt.) through a gastric tube as a 20% (w/v) solution in 0.154 NaCl. Four hours after administration of ethanol liver glutathione content was decreased by 21% when compared to saline-treated controls. A significant reduction (28%) was also found in gamma-glutamylcysteine synthetase activity and plasma glutathione levels were increased non significantly by 17% with respect to control rats. Glutathione S-transferase activity in the liver of ethanol-treated animals was decreased by 28% but no change was found in total glutathione peroxidase activity. The results indicate that the lowered glutathione synthesis could be an important factor contributing to the reduction of hepatic glutathione concentration following the acute ingestion of ethanol.