To study on antioxidant effects of saponin fractions, we investigated effects in the liver of 40-week-old mice to which were pretreated with 5 mg/kg per body weight of saponins for 5 days. The ability of saponins to protect against oxidative damage to the mouse liver was examined by determining the level malondialdehyde (MDA),hydrogen peroxide and the activity of superoxide dismutase (SOD) and catalase (CAT). The only panaxadiol (PD)among the ginseng saponin fractions significantly increased the hepatic SOD activities (p<0.01), Whereas PD, panaxatriol (PT), ginsenoside Rd (G-Rd) (p<0.01) and ginsenoside Re (G-Re) (p<0.05) significantly decreased the contents of hydrogen peroxide. It was only G-Rd that significantly increased CAT activities (p<0.05). The level of MDA was significantly decreased by G-Rd and PD. In conclusion, PD and G-Rd among the saponin fractions were especially increased in the activity of hepatic antioxidative enzyme and decreased the lipid peroxidation that was expressed in term of MDA formation.