Objective: To investigate the effect of tacrolimus on intimal hyperplasia by balloon injury in rat carotid arteries.Methods: At first, 9 rats were randomly selected as sham operation and the model was established by balloon-injured carotid artery in rats, then the survival rats were randomly divided into 2 groups: model groups (n=9) and tacrolimus treatment-group (n=9).Tacrolimus (lmg/kg/d) were offered for 14 days in tacrolimus group, while the sham and model groups were administrated with volume-matched ddH2O instead.After 14 days, HE dyeing was carried out in the blood vessel and the neointimal hyperplasia level and the degree of vascular smooth muscle cell proliferation were evaluated by calculating the neointimal area (NIA) and the NIA/media area (MA) ratio (NIA/MA).The positive expression percentage of NFATC2 in carotid artery intimal was detected by immunohistochemical.Results: Compared with the control group, the arterial intimal hyperplasia (NIA and NIA/MA)and the expression of NFATc2 in carotid artery intimal were significantly increased in the model group (P<0.05).Compared with the model group, the arterial intimal hyperplasia (NIA and NIA/MA) and the expression of NFATc2 in carotid artery intimal were significantly decreased in tacrolimus-treatment group (P < 0.05).Conclusion: Tacrolimus can significantly decrease arterial neointimal hyperplasia after balloon-injury and the mechanism may be related to its inhibition of the expression of NFATc2.