AimTo investigate the expression of angiotensin-coverting enzyme (ACE) , angiotensin-coverting enzyme Ⅱ（ACEⅡ) and the effects of Valsartan on them after vascular balloon injury in rats.MethodsRat models of aortic endothelial denudation were made by an 2F balloon catheter.Rats were randomly allocated into three groups: Group 1 served as controls; Group 2 were given vascular balloon injury; Group 3 were given Valsartan from 1day before injury to 30 days after injury. The expression of ACE mRNA and the level of protein of ACE or ACEⅡ were investigated at day 14 and 30 after injury by reverse transcription polymerse chain reaction (RT-PCR) technique and immunohistochemistry method, respectively. ResultsIntimal thickening was significant at 14 days and 30 days after injury.Valsartan significantly and comparably prevented intimal thickening at 14 days and 30 days after balloon injury.The expression of ACE mRNA and protein was significantly increased at 14 days and 30 days after injury（P<0.05）, while the expression of ACEⅡ protein was significantly increased at 14 days and 30days after injury（P<0.05）.Valsartan can decrease the expression of ACE mRNA and protein and increase the expression of ACEⅡ protein（P<0.05）.ConclusionThe effects of Valsartan on aortic endothelial denudation and regression of vascular remodeling are related with the increased expression of ACEⅡ protein and the decreased expression of ACE.