Backgrounds: The aim of this study was to evaluate the predictors of in-hospital early complication and analysis the relation among these factors in patients with acute myocardial infarction (AMI). Methods: A total of 1,000 consecutive patients (63.4짹12 years, 705 males) with AMI, who were admitted between Mar 2006 and Aug 2007, were divided into two groups according to the presence of in-hospital events; group I associated with events (n= 175, 65.6 짹 12 years, 115 males) vs. group II associated with no events (n=825, 62.8 짹 12 years, 590 males). In-hospital early complications included death, re-infarction, cardiogenic shock, pacemaker implantation, malignant ventricular arrhythmia, and mechanical ventilation. Various clinical, laboratory, echocardiographic parameters and coronary angiographic findings were compared between the two groups. Results: The levels of glucose, creatinine, maximal CK, troponin-I, troponin-T, hs-CRP and NT-pro BNP were significantly increased in group I than in group II (p<0.001). Increased left ventricle end diastolic and systolic dimension, low ejection fraction, mitral regurgitation, diastolic dysfunction, and high wall motion score index were more common in group I than in group II (p<0.001). Initial Killip class, ST-elevation myocardial infarction, the levels of glucose, creatinine, CK-MB, troponin I, hs-CRP, NT-pro BNP and the presence of mitral regurgitation were significant independent predictors of in-hospital events by multivariate analysis. During one-year follow-up, major adverse cardiac event rate was higher in group I than group II (25.4% vs. 12.9%, p<0.001). In-hospital early complications, especially cardiopulmonary resuscitation, cardiogenic shock requiring intra-aortic balloon pump and respiratory failure were independent predictors of MACE during one-year clinical follow-up. Conclusions: High level of glucose, creatinine, CK-MB, troponin I, hs-CRP, NT-pro BNP and presence of mitral regurgitation were significant predictors of in-hospital events in patients with AMI. Long-term MACE free survival was lower in AMI patients suffered from in-hospital events.