AIM:To investigate the change of the endothelial and perivascular cell in an model of diabetic retinopathy (DR), correlate retinal and plasma results and to evaluate the influence of treatment by N-acetylcysteine (NAC) and Tranilast(TNL). METHODS: Five groups were studied: control (Group NOR), streptozotocin (STZ)-induced diabetic rats (Group DM), STZ rats following 12 weeks of NAC (Group NAC), TNL(Group TNL) and both NAC and TNL(Group COM). Plasma levels of superoxide dismutase (SOD) and glutathione(GSH) were obtained. Primary antibodies against tumour necrosis factor-alpha(TNF-α),nuclear factor κB(NF-κB) were used.The retinal vasculature isolated by using the trypsin digest method was observed. RESULTS: Plasma levels of SOD and GSH were lower in Group DM and TNL than the others. Expression of TNF-α was robust in Group DM, mild in Group COM,TNL and NAC, weak in Group NOR. Intensity of NF-κB was higher in Group DM,TNL and NAC compared with Group NOR and COM. The vascular structures of Group COM were much improved than other STZ models. CONCLUSION: Pericyte loss and endothelial cell hyperplasia occur early in DR. These changes are associated with oxidative stress and inflammation and could be minimized by treatment with NAC and TNL. The results suggest that the therapy worked through reducing ROS and inhibiting degranulation of mast cell. This treatment could neutralize the events in diabetic retinopathy in STZ model.