Abstract： AIM　To study the effect of ginsenoside Rg1 on the learning and memory impairment in mice induced by aggregated β-AP(25-35). METHODS　Mice were administered Rg1 (5, 10 mg*kg-1, ip) for 10 d and control mice received daily ip injections of saline after the intracerebroventricular injection of aggregated β-AP(25-35). After the final treatment, passive avoidance and performance in the Morris water maze (MWM) were assessed. and the activity of cortical and hippocampal ChAT and AchE were detected after the final behavior test. RESULTS　Ginsenoside Rg1 (5, 10 mg*kg-1, ip) significantly ameliorated the learning and memory impairment induced by β-AP(25-35). Rg1 (5, 10 mg*kg-1) decreased the latencies and swim distances of mice to reach a hidden platform and improved the corresponding changes in search strategies occurred in the Morris water maze, and Rg1 (10 mg*kg-1, ip), increased step-through latencies also. Biochemical analysis showed that Rg1 (5, 10 mg*kg-1, ip) prevented the cortical and hippocampal ChAT activity decline induced by β- AP(25-35), and showed inhibition of the activity of AchE, although β-AP(25-35) showed no effect on the cortical and hippocampal AchE activity. CONCLUSION　These data showed that ginsenoside Rg1 significantly improved the learning and memory impairment induced by β-AP(25-35), and this effect could be attibuted to its inhibition of AchE and increase of ChAT activity.