Passive avoidance tests have shown that Yizhi Pills (YZ) markedly improve the memory of normal mice at a dose of 100 mg/kg after oral administration for fifteen days, and significantly reverse the scopolamine, NaNO2 and EtOH-induced disruptions of memory retention in mice at doses of 100, 200, 500 mg/kg after oral administration for five days. In aged mice induced by D-galactose, YZ also significantly improve the impaired memory, increase the activity of SOD and decrease the content of MDA in brain. All these effects were observed at doses of 200, 500 mg/kg after oral administration for forty-one days. YZ significantly promote blood carbon particle clearance, enhance hemolysin antibody in immunodepressed mice induced by cyclophosphamide, and increase earswelling in immunodepressed mice induced by prednisolonum.