Abstract: Objective To explore the effects of enalapril on spatial learning and memory, and synaptophysin expression in hippocampus of streptozotocin-diabetic rats. Methods Forty rats were randomly divided into the normal control group, diabetic model group and the enalapril treatment group. Streptozotocin-diabetic rat model was established. The diabetic rats were treated with enalapril for 12 weeks. Then, the learning and memory abilities of rats were tested with the Morris water maze; The mRNA and protein expression levels of synaptophysin in hippocampus were detected by RT-PCR and immunostaining, respectively. Results Compared with diabetic model group, the enalapril treatment group showed a significant decrease in the mean time of escape latencies (P<0.05), an increase in percentage of stay time in the central area and the frequency of passing the original platformposition (P<0.05). In addition, both the levels of synaptophysin protein expression by immunostaining and mRNA expression by RT-PCR increased significantly (p<0.05) in hippocampus of streptozotocin-diabetic rats following enalapril treatment. Conclusion We concluded that enalapril may improve the learning and memory ability by increasing the expression of synaptophysin in the hippocampus of streptozotocin-diabetic rats．