Purpose:To investigate the significance of netrin-1 and vascular endothelial growth factor(VEGF) in the pathogenesis of retinal angiogenesis,the levels of netrin-1 and VEGF in the vitreous fluid and serum of the proliferative diabetic retinopathy (PDR) and non-proliferative diabetic retinopathy (non-PDR) patients were measured. We then determined the netrin-1 and VEGF expression in the oxygen induced retinopathy (OIR) mice retina. Methods:A total of 18 eyes from 18 patients were included in our study and 10 of them were collected from PDR patients and 8 from non-PDR patients. Undiluted vitreous fluid samples were collected during pars plana vitrectomy. Appropriate blood samples were collected if possible. Netrin-1 and VEGF levels in the vitreous fluid and plasma were determined by Enzyme-linked Immunosorbent Assays.OIR mice models were established,and netrin-1 and VEGF levels were determined by immunohistochemistry analysis. Results:The levels of netrin-1 and VEGF in the vitreous of PDR patients were significantly higher than those in the controls (Mediannetrin-1=509.94 vs.85.91 pg/ml,P<0.001 and MedianVEGF=762.60 vs.77.52 pg/ml,P<0.001). Netrin1 was mainly expressed in GCL and INL of the retina in mice.Both netrin-1 and VEGF were up-regulated in OIR mice. Conclusion:Netrin-1 and VEGF levels were elevated in vitreous fluid of the PDR patients and the OIR mice retina. Therefore,netrin-1 may play an important role in pathological retinal angiogenesis. Purpose: To investigate the significance of netrin-1 and vascular endothelial growth factor (VEGF) in the pathogenesis of retinal angiogenesis, the levels of netrin-1 and VEGF in the vitreous fluid and serum of the proliferative diabetic retinopathy (PDR) and non- We then determined the netrin-1 and VEGF expression in the oxygen induced retinopathy (OIR) mice retina. Methods: A total of 18 eyes from 18 patients were included in our study and 10 of them were collected from PDR patients and 8 from non-PDR patients. Undiluted vitreous fluid samples were collected during pars plana vitrectomy. Appropriate blood samples were collected if possible. Netrin-1 and VEGF levels in the vitreous fluid were determined by Enzyme -linked Immunosorbent Assays. OIR mice models were established, and netrin-1 and VEGF levels were determined by immunohistochemistry. Results: The levels of netrin-1 and VEGF in the vitreous of PD R patients were significantly higher than those in the controls (Mediannetrin-1 = 509.94 vs.85.91 pg / ml, P <0.001 and Median VEGF = 762.60 vs.77.52 pg / ml, P <0.001). Netrin 1 was mainly expressed in GCL and INL of the retina in mice. Both netrin-1 and VEGF were up-regulated in OIR mice. Conclusion: Netrin-1 and VEGF levels were elevated in vitreous fluid of the PDR patients and the OIR mice retina. Thus, netrin-1 may play an important role in pathological retinal angiogenesis.