Effects of siho(Bupleuri Radix) extracts on lipid composition and antioxidant system were investigated in rat fed high fat diet. body weight gain, concentration of plasma triglyceride, total cholesterol, LDL-cholesterol showed a tendency to decrease in siho(Bupleuri Radix) extracts groups. However, the concentration of HDL-cholesterol showed no significantly different among treatments. Plasma and liver TBARS concentration showed a low values in siho(Bupleuri Radix) extracts groups. Activities of SOD, GSH-Px and CAT showed a tendency to increase in siho(Bupleuri Radix) extracts groups.