Objectives : Ojayeonjonghwan(五子衍宗丸) is composed of Polygonum multiflorum THUNB, and some medical herbs that are known as formula of senescence delay effects. The purpose of this study is to investigate th effect of Ojayeonjonghwan on antioxidant enzyme activities, such as Thiobarbituric acid reactive substance(TBARS), Superoxide dismutase(SOD), Catalase(CAT), Glutathione preoxidase (GSH-px) in rat erythrocytes and blood plasma. Methods : Sprague-Dawley rats were divided into 3 groups, Normal group (supplied enough water and feeds only, Normal Group), D-galatose administered group(injected D-galatose 50mg/kg, 1time/day for 6 weeks, Control Group) and Ojayeonjonghwan administered group (D-galactose 50mg/kg and Ojayeonjonghwan extracts 245.0mg/200g 1time/day for 6 weeks, OJY Group). Rats were sacrificed and TBARS, SOD, CAT, GSH-px, Plasma total lipid, Plasma triglyceride and cholesterol were measured in rat erythrocytes and blood plasma. Results : TBARS in plasma concentration of OJY group was significantly lower than that of control group. Red blood cell(RBC) SOD activity of OJY group was significantly higher than that of control group(F=16.057, p=0.0001, ANOVA test), RBC GSH-px activity of OJY group was increased(F=4.271, p=0.034, ANOVA test). RBC catalase activities of all experimental group were not significantly different. Total lipid and triglyceride concentration in plasma of all experimental groups were not significantly different. Total cholesterol concentrations in plasma of OJY group were significantly lower than those of control group(F=4.387, p=0.032, ANOVA test). Conclusions : According to the above results, it is considered that Ojayeonjonghwan is effective in inhibiting lipid peroxidation and increasing antioxidative enzyme activities in D-galactose induced aging rat.