Background: Bifurcation lesions (BF) remains a challenging lesion subset, often associated with lower success rates. There are limited data regarding the clinical outcomes of bifurcation lesions in the acute myocardial infarction (AMI). We compared clinical outcomes between BF and non BF lesions in AMI patients undergoing primary percutaneous coronary intervention (PCI). Methods: A total of 903 patients were performed primary percutaneous intervention for AMI between January 2004 and April 2009, and the patients were divided into two groups according to presence or absence of a BF in the infarct-related artery : BF group (n= 332) and non BF (n=571). BF were defined as a ���2.0 mm side branch (SB). Results: The baseline clinical characteristics of patients were similar between two groups except male gender was higher in BF group (76.2% vs 68.1%, p=0.01) and non ST elevation myocardial infarction (NSTEMI) were higher in BF group (51.5% vs 60.4%, p=0.01). Baseline angiographic characteristics showed that the BF group had higher incidences of culprit lesion in left anterior descending artery (LAD, 65.4% vs 49.1%, p<0.001), left circumflex artery (LCX, 40.7% vs 24.1%, p<0.001), and left main (13.6% vs 1.6%, p<0.001). Peak values of troponin T and CK-MB, BNP, and LVEF were similar between two groups. At 24 months, the incidence of total death, cardiac death, STEMI, and major adverse cardiac events (MACE)s were similar between two groups, but the incidence of target lesion revascularization (TLR) and taget vessel revascularization (TVR) at 24 months were higher in BF group (Table1). Conclusion:Despite being challenging lesions, bifurcations in the setting of AMI was associated with similar mid term angiographic and long term angiographic outcome, but lead to significantly higher incidence of revascularization including TLR and TVR during 24 month follow up as compared to non BF lesions