Background: Contrast-induced nephropathy (CIN) is associated with higher in-hospital complication rate and mortality in patients with acute myocardial infarction (AMI) undergoing percutaneous coronary intervention (PCI). We investigated the long-term prognostic implications of CIN in patients with AMI treated with PCI. Methods: This study retrospectively analyzed clinical data of 1,044 patients (male 751 (72%), age: 62.7 짹 12.2 years) from the Severance Cardiovascular Hospital AMI registry cohort who underwent PCI between May 2005 and July 2009. CIN was defined as an increase in serum creatinine (sCr) of >25% or >0.5 mg/dl within 2 days after PCI. The primary endpoint, major adverse cardio-renal events (MACE), is defined as the composite of death, re-infarction, target vessel lesion revascularization, congestive heart failure requiring hospital admission, stroke, and renal failure requiring dialysis. Results: Overall, 148 patients (14.2%) developed CIN. Multivariate analysis showed that female gender, age >75 years, chronic renal failure, diabetes, and left ventricular ejection fraction (LVEF) <40% were independent risk factors of CIN. Patients developing CIN had a significantly longer hospital stay (14.7 vs. 8.5 days, p<0.001) and higher MACE (18% vs. 4%, p<0.001) and mortality rates (15% vs. 3%, p<0.001) at 1 month than those without CIN. The 2-year MACE (41% vs. 21%, p<0.001) and mortality rates (29% vs. 8%, p<0.001) were also higher in the CIN group compared to the patient group without CIN. The patients whose renal function was recovered showed a higher 2-year MACE-free survival rate than those without renal function recovery (78% vs. 58%, p=0.043), but had a trend toward lower MACE-free survival than the patients without CIN (78% vs. 83%, p=0.093). In a multivariate Cox regression analysis, CIN was identified as the independent predictor of the MACE (hazard ratio [HR] 1.52, 95% confidence interval [CI] 1.04 to 2.23, p=0.033) and death (HR 2.87, 95% CI 1.72 to 4.78, p<0.001) after adjusting for confounding variables such as sex, age, pre-PCI sCr, LVEF, and comorbidities. Conclusion: CIN was not only associated with increased in-hospital mortality and morbidity, but also with higher long-term MACE and mortality rates. Thus, better preventive strategies are needed to improve clinical outcomes in AMI patients at high risk of developing CIN due to various predisposing factors.