Objectives : CRATAEGII FRUCTUS(山査) is known as the substance which delays aging by the antioxidant effects. The purpose of this study is to investigate the effects of CRATAEGII FRUCTUS(山査) on antioxidant enzyme activities such as Thiobarbituric acid reactive substance(TBARS), Superoxide dismutase(SOD), Catalase(CAT), Glutathione peroxidase (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 CRATAEGII FRUCTUS(山査) administered group (D-galactose 50mg/kg and CRATAEGII FRUCTUS(山査) extracts 85.0mg/200g 1time/day for 6 weeks, SS Group). Rats were sacrificed and TBARS, SOD, CAT, GSH-px, neutral fat and cholesterol were measured in rat erythrocytes and blood plasma. Results : There was no significant difference in the level of TBARS in the blood plasma between each experimental group. Red blood cell SOD activities were significantly different in each group. They were significantly decreased in the Control group compared to those of Normal and there was an increasing phenomenon in the SS group compared to the Control group. There was a significant difference in the activities of the red blood cell - glutathione peroxides in each group. There was a significant increase in the SS group compared to the Control group. Red blood cell catalase activities was no significant difference in each group. Plasma total lipid concentration was significantly different in each group. It was significantly increased in the Control group compared with the Normal group and it was decreasing in the SS group compared to the control group. Plasma triglyceride was not significantly different in each group. Plasma total cholesterol and Plasma HDL -cholesterol concentrations in the blood plasma were not significantly different in each group. Conclusions : According to the above results, it is considered that CRATAEGII FRUCTUS(山査) is effective in inhibiting lipid peroxides and increasing the activities of antioxidative(anti aging) enzyme in D-galactose induced aging rat.