Abstract: Objective To study the effects of aluminum trichloride on learning memory and apoptosis of hippocam puscell.Methods Sprague-Dawley rats were randomly divided into four groups based on the ir boby weight.Aluminum chloride was added into dietat doses of 0,11.2,55.9and 111.9mg/kg·bw for 90 days successively.L earning and memorya bilities were observed by Y-maze.The morphological characters and percent of neuronal apop tosis in hippocam pus were identified by teminal deoxynuleotidyl transferase-mediated nick-end labeling(TUN EL)and FACS scan.A luminum was measured by a tomic absorption spectroscopy.Results Correct escaping rate of the ratsin the dose group of 111.9mg Al³⁺/kg·bw was decreased.And escaping latency of rats exposed to doses of 55.9 and 111.9m g/kg·bw was prolonged significantly as compared with the controls.In hippocampus,TUN EL-positive cell could be detected in every treatment group.As the dosage of AlC l3 increased,TUN EL-positive appeared to be more obvious.The rates of apoptosis and luminum content in hippocampus in every treatment group were significantly increased with a singificant does-resp onse relationsh ip.Conclusion A poptosis induced by a luminum in rathippocampus might be one of the important mechanisms of the damage of learning and memory.