Objectives : In order to examine the antioxidant activities of Kyungohkgo(瓊玉膏), the study was done through measurement of parameters such as Thiobarbituric acid reactive substance(TBARS), Superoxide dismutase(SOD), Catalase(CAT), Glutathione peroxidase(GSH-px), Plasma total lipid, Plasma total triglyceride, Plasma total cholesterol, HDL-cholesterol concentrations in rat erythrocytes and plasma. Methods : Sprague-Dawley rats divided into 3 groups, Normal group(l2 weeks old), pathologically induced group(injected D-galatose 50mg/kg, 1time/day for 6 weeks, CONTROL) and Kyungohkgo(瓊玉膏) administered group(D-galactose 50mg/kg and Kyungohkgo extracts 1125.0mg/kg 1time/day for 6 weeks, KOG). Rats were sacrificed and TBARS, SOD, CAT, Plasma total lipid, Plasma triglyceride, Plasma total cholesterol, Plasma HDL-cholesterol concentrations and GSH-px were measured in rat erythrocytes and plasma. Results : Plasma TBARS concentrations of KOG group were significantly lower than those of control. Red blood cell(RBC) SOD activities of KOG group was increased(F=3.619, p=0.052, ANOVA test), and RBC catalase activities of all experimental group were not significantly different. RBC GSH-px activities of KOG group was increased(F=6.844, p=0.008, ANOVA test). The changes of Plasma triglyceride was not significantly different. Plasma total lipid of KOG group showed significant decrease compared to the control group(F=19.337, p=0.0001, ANOVA test). Plasma total cholesterol and HDL-cholesterol concentrations of all experimental groups were not significantly different. Conclusions : According to the above results, it is considered that Kyungohkgo(瓊玉膏) is effective in inhibiting lipid peroxidation and increasing antioxidative enzyme activities in D-galactose induced aging rat.