Object : This study was carried out to examine the effect of Bupleuri Radix on experimental cholestasis, and make clear apart of this mechanism. Methods : Two models of common bile duct ligation group and taurocholate load group after common bile duct ligation were induced, and Bupleuri Radix extract was taken orally for 14 days. In the 1, 2, 4, 7 and 14 days after treatment, the mitochondrial and microsomal monoamine oxidase(MAO) A and B activities in liver were measured. Results : The mitochondrial MAO A and B activities increased in both Blupleuri Radix treated group after common bile duct ligation and Blupleuri Radix treated group after taurocholate load and common bile duct ligation. MAO A increased in Blupleuri Radix treated group after taurocholate load and common bile duct ligation, and MAO B increased in Blupleuri Radix treated group after common bile duct ligation. The microsomal MAO A activities increased in both Blupleuri Radix treated group after common bile duct ligation and Blupleuri Radix treated group after taurocholate load and common bile duct ligation. Conclusion : According to the result, it is consider that Blupleuri Radix not only improves cholestatis in liver, but also decreases a genetic synthesis of taurocholic acid.