Abstract: In order to study the pathogenesis of hepatic fibrosis, serum monoamine oxidase, mucoprotein, plasma proline and hydroxyproline were determined on 7 rabbits infected with Schistosoma japonicum. After infection serum monoamine oxidase and mucoprotein increased markedly, while plasm hydroxyproline and proline decreased evidently. After pyquiton treatment serum mucoprotein rapidly decreased and returned to normal level; whereas serum monoamine oxidase also diminished significantly, but didn't return to normal. It is suggested these biochemical indices might be of value in the early diagnosis of hepatic fibrosis and the evaluation of the effectiveness of therapy in schistosomiasis.