Objectives: This study was undertaken to investigate the action mechanism of Holotrichia (HT) at parameter related to dementia. Methods: HT was tested for the effects on acetylchonine esterase and monoamine oxidase activities, lipid peroxidation, antioxidation in brain of lead acetate-treated rats. Lead acetate were treated firstly into samples for 10 days, and then lead acetate and HT were set with them for 20 days. Results: The level of lipid peroxide, acetylcholine esterase and monoamine oxidase activities, enzyme activities and ratio of type conversion of xanthine oxidase increased in lead acetate-treated rats were decreased as highly as normal group by HT. Superoxide dismutase, catalase and glutathione peroxidase activities, the level of acetylcholine decreased in lead acetate-treated rats were increased as lowly as normal group by HT. Conclusions : These results suggest that HT might have an effect on treatment of dementia according to decreasing the activities of acetylcholine esterase, monoamine oxidase and level of lipid peroxide in brain.