Aim To investigate the effect of resveratrol on reendothelialization and intimal hyperplasia in balloon injured aorta of rat and its potential mechanism. Methods 54 healthy male Sprague-Dawley rats were randomly divided into 4 groups: sham operation group(n=9),placebo-treated group(n=15),small dose resveratrol [10 mg/(kg·d)] group(n=15) and large dose resveratrol [50 mg/(kg·d)] group(n=15).Rats were gavaged with resveratrol or placebo 2 weeks before balloon injury until sacrificed.At 1 and 2 weeks after endothelium denudation,Ⅷ factor immunohistochemical staining and Evans blue staining were used to measure the reendothelialized area.Neointimal formation was determined by HE staining at 2 and 4 weeks after operation.At 1 and 4 weeks after artery injury,endothelial nitric oxide synthase(eNOS) mRNA and protein expression were assayed by reverse transcription-polymerase chain reaction(RT-PCR) and immunohistochemistry,respectively. Endothelial progenitor cells(EPC) were isolated and cultured from rat peripheral blood,which were identified by immunohistochemistry,then the amount of EPC at 1 week after balloon injury were measured by counting DiI-acLDL/FITC-UEA-Ⅰdoublepositive cells in inverted fluorescence microscope. Results 10 mg/(kg·d) resveratrol significantly accelerated reendothelialization at 1 and 2 weeks after balloon injury,50 mg/(kg·d)could not.10 mg/(kg·d) resveratrol markedly inhibited neointimal formation at 2 and 4 weeks after operation,however,50 mg/(kg·d) only reduced neointimal formation at 4 weeks after operation,which was not as effective as previous one.The expressions of eNOS mRNA and protein were potently enhanced in 10 mg/(kg·d) resveratrol group,but not in 50 mg/(kg·d) group.10 mg/(kg·d) resveratrol also significantly increased the amount of EPC in rat peripheral blood at 1 week after operation compared with placebo-treated group(32.46±6.52 vs 21.58±3.69,p<0.05),while the results of 50 mg/kg group did not reach statistical difference(22.48±6.89 vs 21.58±3.69,p<0.05). Conclusions Small dose resveratrol could markedly increase the expression of eNOS,enhance the mobilization of EPC as well as accelerate reendothelialization and reduce neointimal formation compared with placebo-treated group.However,large dose resveratrol only attenuated the intimal hyperplasia at 4 weeks after operation.