Introduction : Transient advanced AV block was frequently observed in patient with acute myocardial infarction. We aimed to clarify predictive value of advanced AV block in patient with acute myocardial infarction from large volume nationwide registry data. Methods : We analyzed 7001 patients (male 69.4%, Age 62.7짹12.6 yr) who were presented with acute myocardial infarction from KAMIR. We checked baseline characteristics, laboratory, echocardiographic and angiographic findings. We divided patients into two groups as presence of advanced AV block (more than 2nd degree AV block). Various parameters and clinical outcomes during 1 year follow up were assessed. Results : 233 patients (3.3%) had advanced AV block in initial ECG. In baseline clinical characteristics, patients with AV block had higher incidence of advanced Killip class (35.8% with AV block group vs 12.8% without AV block group, p<0.001). Coronary risk factors such as hypertension, DM and hyperlipidemia were more frequently observed in patients with AV block. Coronary angiography showed more frequent RCA involvement (76.0% vs 27.7%, p<0.001) and TIMI 0 flow (60.5% vs 37.7%) in AV block group. There was no statistically significant difference in laboratory, echocardiographic findings between two groups. Advanced AV block was associated with higher in-hospital mortality (22.7% vs 7.3%, p<0.0012). But in long term survival analysis adjusted by multivariate cox regression, presence of advanced AV block was not independent predictor of death/myocardial infarction (p=0.301) and MACE (p=0.987) during 1 year follow up. Conclusion : The presence of advanced AV block in acute myocardial infarction was associated with advanced Killip class, unfavorable coronary angiographic finding and higher in-hospital mortality. But there was no significant difference in long term clinical outcome according to advanced AV block.