Background and Objectives: Endothelial dysfunction plays a key role in atherogenesis and predicts future cardiovascular events in subjects with and without coronary artery disease. This study was designed to evaluate the relation between endothelial dysfunction and major adverse cardiovascular event (MACE) in patients undergoing PCI. Subjects and Methods: 2-years follow-up was obtained in 182 patients (59짹10 year, 120 men) undergoing PCI and 6-month follow-up coronary angiography after PCI. All patients underwent ultrasound detection of brachial artery flow-mediated dilation (FMD) before PCI and were evaluated MACE. Results: 66 patients had 74 MACE: 3 myocardial infarction, 7 cerebrovascular event, 49 target vessel revascularization, 2 coronary artery bypass graft, 13 new lesion PCI. FMD was no significant differences in patients with an event or without event (3.9짹2.3% vs. 4.1짹2.1%, p>0.05). The cerebrovascular event rate was significantly higher in patients with FMD below the median than those with FMD above the median (7 vs. 0, p=0.005). But, no significant differences was found in MI (1 vs. 2), TLR (28 vs. 21), new lesion PCI (6 vs. 7), CABG (0 vs. 2) and cardiac death rate (0 vs. 0) according to FMD below and above the median (p>0.05). In the multivariate Cox regression analysis, FMD was the strongest predictor of cerebrovascular event (OR 0.418, 95% CI 0.185 to 0.940, p=0.035). Conclusion: Impaired flow-mediated dilation independently predicits occurrence of cerebrovascular event in patients undergoing PCI.