Effects of powdered siho(bupleuri radix) on serum and liver lipid composition and antioxidative capacity were investigated in rat fed high oxidized fat. Sixty male Sprague-Dawley rats weighing 161.25$pm$2.51g were blocked into four groups according to body weight and raised seven weeks with basal diet(normal group), basal diet and 10% oxidized fat(control group), basal diet, 10% oxidized fat and 2% powdered siho(2% powdered siho group) and basal diet, 10% oxidized fat and 3% powdered siho(3% powdered siho group). Feed intake, body weight gain and feed efficiency were not significantly different among oxidized fat diet groups. The values of total cholesterol and triglyceride in plasma and liver showed no significantly different(p>0.05) in the oxidized fat diet groups. Plasma HDL-cholesterol showed atendency to increase in powdered siho diet groups. The values of thiobarbituric acid in plasma and liver were lower in the powdered siho diet groups than control group. Plasma GOT and GPT activity showed a tendence to decrease in powdered siho groups. Liver glutathione peroxidase activity showed a tendence to increase in powdered siho diet groups. Thus, it seems that powdered siho had some antioxidative elements.