Objective To observe the expression of the pigment epithelium derived growth factor (PEDF) in retina and the effects of PEDF for vascular endothelial growth factor (VEGF) and retinal microvascular after recombinant adeno-associated virus mediated pigment epithelium derived factor（rAAV-mediated-PEDF）transferred retina of diabetic rats. Methods Male Wister rats were induced diabetes with intraperitoneal injection of streptozocin, then divided into 1 month group (DM1), 3month group(DM3) and 6 month group randomly. In diabetic rats, right eyes were injected rAAV2CMVhPEDF into vitreum as treat group,left eyes were injected into rAAV2-CMV-GFP (1times;1011 v.g/ml) as self-control group. In normal rats, right eyes were punctured but not injected (CONf), left eyes let it be without any disposal. The levels of VEGFmRNA and hPEDFmRNA in retina were evaluated using RT-PCR in different period. The protein levels of VEGF, PEDF within the retina were determined using western blot. The change of retinal capillary were observed through retinal vascular flattening. Result The expression of hPEDFmRNA in retina was enhanced persistence after rAAV2-CMV-hPEDF injected, achieved climax until 6 months. The levels of PEDF were also incerased consecutive, the differences were statistically significant in treatment group compared with own control group （Plt;0.01）. Levels of mRNA and protein of VEGF at different time-points among therapy group were not statistically significant, all obviously higher than normal （Plt;0.05），but all lower obviously than respectively own control group at the same timepoint （Plt;0.01）. The morphology of retinal capillary was not different significant with normal rats in 1 month diabetic rats. Morphology changes of therapy groups were less than those of respective own control group in DM3 and DM6. Conclusion Intravitreous injection rAAV2-CMV-hPEDF can increase expression of mRNA and protein of PEDF，alleviate lesion of retinal microvascular in early period of diabetic rats and supress expression of VEGF in retina of diabetic rats.The regulation occur on mRNA level. （Chin J Ocul Fundus Dis，2008，24：259-264）