Backgrounds: The correlation of periprocedural myocardial infarction (PPMI) with major adverse cardiac events (MACE) is controversial in previous studies. We investigated the significance of PPMI on cardiac outcomes of patients who underwent percutaneous coronary intervention (PCI) with drug eluting stent (DES). Method: Among 6,749 consecutive patients who underwent PCI with DES form January 2004 to December 2009 in the COACT (CathOlic medical center percutAneous Coronary intervention) Registry, we reviewed 3,781 patients with stable or unstable angina who had successful PCI with DES. We analyzed the clinical outcomes according to the existence of PPMI. PPMI was defined as peak CK-MB level more than 15 IU per liter after PCI. The primary end point was a composite of MACE including cardiac death, myocardial infarction, and target vessel revascularization. Results: Mean follow-up duration was 755 짹 548 days. The incidence of PPMI was 7.4% (n=283). Patients with PPMI have more past history of hypertension (71% vs. 64.2%, p=0.021) and diabetes (43.5% vs. 37.6%, p=0.049) than those without PPMI. Patients with PPMI are older (66.28 짹 9.88 vs. 64.03 짹 10.12), and have more multi-vessel disease (71.4% vs. 53.5%). PPMI was a significant independent predictor of MACE (adjusted hazard ratio 1.607, 95% confidence interval 1.172 to 2.203, p=0.003). Conclusion: PPMI is associated with cardiovascular events in patients who underwent PCI with DES.