Aim To investgate the effect of granulocyte colony-stimulating factor(G-CSF) on reendothelialization and neointimal hyperplasia in balloon injured carotid of rat,and explore its potential mechanism. Methods 36 Wistar rats were randomly divided into three groups: sham operation group(n=12),G-CSF group(n=12) and placebo group(n=12).The balloon-injured carotid model was established in G-CSF group and placebo group,G-CSF 100 μg/(kg·d)] was intraperitoneal injected in G-CSF group from the point at operation to 2 weeks after operation,saline was administrated in placebo group.After two weeks,the neointima/media area ratio(IA/MA),repair rate of injuried endothelium,the proliferating cell nuclear antigen(PCNA) positive cell ratio and nitric oxide(NO) release in vessel homogenate were detected in three groups.In addition,the ratio of CD34+VEGFR-2+ double positive cell was detected by FACS. Results Compared with the placebo group,the IA/MA and PCNA positive cell ratio were reduced(1.04±0.05 vs 1.67±0.07,21.3%±5.1% vs 34.4%±6.1%,respectively,P<0.05);repair rate of injuried endothelium and NO release increased(70.1%±4.6% vs 53.2%±3.8%,71.3±12.9 μmol/L vs 56.7±10.8 μmol/L,P<0.05) in G-CSF group.The ratio of CD34+VEGFR-2+ double positive cell of G-CSF group was higher than that of placebo group(0.954%±0.076% vs 0.379%±0.052%,P<0.05). Conclusions The results suggested that G-CSF may increase the ratio of EPC in peripheral blood by mobilizing the bone marrow,then improve the effect of repair rate of injuried endothelium and inhibit neointimal hyperplasia.