Objective To study the effects of Huan Shao Dan on monoamine oxidase activity in brian and liver tissues of rats. Methods Uv spectrophotometry was taken to determine the activity of MAO-B in brian and liver tissues of rats. Results It is observed that the activity of MAO- B was increased in brain and liver tissues of old rats significantly than young ones( P 〈 0. 01 ). The activity of MAO- B in Huan Shao Dan groups of big and little aging rats was decreased significantly than that in the saline groups ( P 〈 0. O1 ). Conclusions Huan Shao ...