Effect of ginseng butanol fractions on the hepatic mitochondrial monoamine oxidase activity with ethanol treatment was investigated in this experiment. Ethanol treatment, either acutely or chronically, increased the hepatic mitochondrial monoamine oxidase activity compared to control group. Whereas, treatment with ginseng butanol fractions lowered the ethaol-induced monoamine oxidase activity. Acetaldehyde, the major metabolite of ethanol, significantly increased the hepatic mitochondrial monoamine oxidase activity more than ethanol did. It was also observed that ginseng butanol fractions reduced the increase of the hepatic mitochondial monoamine oxidase activity by acetaldehyde. From these results, it is suggested that ginseng butanol fractions may be associated with the modulation of the hepatic mitochondrial monoamine oxidase activity in ethanol-treated animals.