Objective To investigate the effects of electroacupuncture (EA) on spatial learning and memory ability, long-term potentiation (LTP) and synaptophysin (Syp) levels in the dentate gyrus of the hippocampus.Methods Forty Sprague-Dawley rats were randomly divided into a sham-operated control group, a model group, an EA group and a medication group. A rat model of vascular dementia (VD) was established by repeated ischemia and reperfusion after pretreatment with sodium nitroprusside. EA was applied to the rat homologues of the human "Baihui" (GV20) and "Dazhui" (DU14) acupoints of the rats in the EA group for 20 min, once daily for 10 d.Morris water maze tests were conducted for evaluating the rats,learning and memory ability. LTP in the hippocampal dentate gyrus was recorded as an electrophysiological index for evaluating learning and memory. Antigenic Syp produced in hippocampal tissue was examined with immunohistochemical assays. Results In comparison the with model group, escape latency (EL) shortened and target-platform crossing times increased significantly in the EA and medication groups. After high frequency stimulation the population spike (PS) latency shortened in the EA group compared with the model group, and the excitatory postsynaptic potential (EPSP) slope and PS amplitude increased.All of these differences were statistically significant. Syp positive cells also increased significantly in the EA-treated rats. Conclusions EA can increase Syp expression and improve the learning and memory ability of rats with this model of VD. EA could facilitate the induction and maintenance of LTP in the dentate gyrus of the hippocampus through influencing synaptic transmission.