Objective：To observe the changes of visual evoked potential (VEP) in diabetic rats and the influence of nerve growth factor (NGF) and aminoguanidine (AG) on VEP.Methods: Diabetes was induced in adult male Wistar rats with streptozotocin (STZ).Rats were divided into normal control group (CON),diabetes model group (DM),NGF-treated group (D+N) and AG-treated group(D+A).VEP was measured during the 3rd month,6th month, 9th month,and 12th month.Results: Compared with the CON group,all rest groups had longer latencies and lower amplitudes (P<0.01).During the 6th and 9th months, the latencies in group D+N and group D+A were significantly decreased (P<0.05) compared with DM group, and the amplitude was partially recoved during the 6th month.The changes during the 12th month were similar to those of the 9th month, except that the amplitude in D+A group was slightly higher than that in the DM group.Conclusion: NGF and AG can improve DM-induced elongation of VEP latency and decrease of VEP amplitude.