The investigation was aimed to study the effect of ginseng ethanol extract on the hepatic ethanol-metabolizing enzyme activity in vivo. The extract (100mg/kg/day) was administered orally to Sprague-Dawley rats for $7{sim}10$ days and their microsomal ethanol oxidizing system(MEOS) and catalase activities were measured. The MEOS activity in the rat treated with the extract was not significantly different from that of the normal group. Microsomal fraction containing MEOS was separated and the MEOS activity was measured after preincubation for 5, 60 and 180 min, respectively. There were no significant differences in MEOS activities between the normal and treated groups preincubated for 5, 60 and 180 min. The activity in the rat treated with single i.p. injection of 95% $CCl_4$ (0.5ml/kg) was decreased by 48%, compared to the normal group and in the rat treated with the extract (100mg/kg) for $7{sim}10$ days, the decrease of the MEOS activity was potentiated. Catalase activity in the rat treated with the extract (100mg/kg) was similar to that obtained from the normal group.