Objective:To assess the role of NADPH oxidase-related oxidative stress in the intimal hyperplasia induced by adventitial injury.Methods: Animal model of vascular adventitial injury was established by combining collogenase digestion and mechanical dissection.HE staining was used to observe the morphological changes of the vessels after adventitial injury; RT-PCR was used to examine the mRNA expression of NADPH oxidase subunit p22phox and antioxidant heme oxygenase-1; and fluorescence probe was employed to detect the ROS production in the vessels.Results: Adventitial injuries could induce intimal hyperplasia lesions in the vessels;they also led to the elevated expression of p22phox/HO-1 mRNA and increased production of ROS.Conclusion: The vascular adventitia is involved in the pathological process of intimal hyperplasia,and oxidative stress caused by increased NADPH oxidase activity may be one of the mechanisms.