Aim To investigate the effect of chitosan on the endothelial regeneration and neointimal proliferation after balloon angioplasty of right carotid artery in rat. Methods Endothelial denudation of artery in rat were performed with 2F balloon catheter. 50 SD rats were randomly divided into the modle group and the chitosan group. Artery were harvested on 0 d, 7 d, 14 d, 28 d and 35 d after the injury, respectively. The reendothelialization and the neointimal hyperplasia were observed cross-sections stained with hematoxylin-eosin from the injured segments processed for histological and morphological study by computer-assisted picture analysis system. Results Chitosan enhanced the reendothelialization of the injured arterial determined vascular endothelial growth factor (VEGF) staining. The absolute reendothelialization was observed on 14 d in chitosan group but on 28 d in the modle group. Intimal hyperplasia and lumen stenosis can be seen on the 7 d after injury. At the 28th day the intimal thicken reached at a peak. In the chitosan group the intimal thicken reached at a peak at the 14 th day. There were significant difference of neointimal in the chitosan group and the modle group on the 14th day, 28th day and 35th day. Conclusions Chitosan is effective on intimal hyperplasia and lumen stenosis after arterial injury by inhibiting neointimal proliferation which is related to the reendothelialiazation.