Inducible nitric oxide synthase (iNOS) is involved in the oxidation stress induced by peroxynitrite (ONOO^－) in rat retina pigment epithelial (RPE) cells.The purpose of this study was to explore  that if ONOO^－induced iNOS via Fas/ Fas/L pathway in streptozotocin(STZ) -induced diabetic rats and the effection of puerarin as therapeutic agent for decrease diabetic retinopathy. Thirty-six rats were taken as control group, seventy two were given STZ (45mg/kg) and then divided into ONOO^－ group and puerarin group (peritoneal injection puerarin). STZ-induced diabetic rats were treated with puerarin for 60 days. Western blotting analysis, DNA ladder, RT-PCR, immunohistochemistry and flow cytometry were used for determining the expression of nitrotyrosine (NT, the foot print of ONOO^－); apoptosis and iNOS mRNA as well as Fas/Fasl signal transduction in RPE cells. Both RPE cells in ONOO^－ and puerarin group developed apoptosis and expressed NT, iNOS mRNA and Fas/Fasl. But latter delayed the all changes in a time-dependent manner compared with control and ONOO^－ group (P＜0.001). iNOS and Fas/Fasl were up-regulated and associated with an increase of expression of ONOO^－in vivo. Which suggested that apoptosis of RPE was partly induced by ONOO^－ may be the new way of oxidative damage to the RPE cells. Puerarin decreased RPE cells apoptosis partly induced by ONOO^－ and is a potential drug for therapy of diabetic retinopathy. The mechanism of puerarin dealing with RPE cells may be related to its direct inhibition of the formation of iNOS to produce ONOO^－ and antagnism of damage of ONOO^－ to RPE cells.