Background: No-reflow phenomenon has been known as a poor prognostic indicator after percutaneous coronary intervention (PCI). However, the long-term clinical significance of no-reflow occurred during PCI in drug-eluting stent (DES) era has not been well known. The purpose of this study was to evaluate the long-term clinical impact of no-reflow occurred during PCI with DES. Methods: From March 2003 to July 2008, a total of 2047 patients (1353 males, age 62.4짹10.4 years) who underwent PCI with DES were included. In this study, no-reflow was defined as TIMI flow 0 – 2 after DES implantation. Comparison of clinical outcomes at one year according to presence of no-reflow during PCI with DES was performed. The primary endpoint was the cumulative incidence of cardiovascular events including death, myocardial infarction (MI), target vessel revascularization (TVR) and stent thrombosis (ST). Results: No-reflow phenomenon was occurred in 51 of 2047 patients (2.5%). The patients with no-reflow showed higher incidence of combined events (17.6% vs 7.9%, p=0.019) and deaths (17.6% vs 2.4%, p<0.001) during 1-year follow-up. Univariate analysis showed that the patients in whom no-reflow developed were more likely to have older age (odd ratio (OR) 1.140, p=0.009), lower ejection fraction (OR 0.971, p=0.014) and presentation with an acute coronary syndrome (OR 2.716, p=0.010). The patients who underwent primary PCI also had a higher risk of no-reflow (OR 4.467, p<0.001). In multivariate analysis, older age (OR 1.034, p=0.020) and performing primary PCI (OR 4.270, p<0.001) were independent predictor of no-reflow. Conclusion: No-reflow phenomenon during PCI is associated with poor long-term clinical outcomes in DES era.