Background and Objectives The aim of this study is to compare clinical outcomes of patients presented left circumflex artery (LCX) related ST elevation myocardial infarction (STEMI) with non-STEMI. Materials and Methods A total 158 patients who were diagnosed as acute myocardial infarction in LCX���territory and performed percutaneous coronary intervention (PCI) were enrolled. Group 1 (n=119) was defined as patients presented without ST segment elevation on initial electrocardiogram, Group 2 (n=39) with ST segment elevation. Primary end-points were major adverse cardiac events (MACE) such as cardiac death, myocardial infarction, target vessel revascularization (TVR), target lesion revascularization (TLR) and stent thrombosis (ST) for 18 months. Results Baseline characteristics was similar between two groups. The rate of total occlusion was higher in Group 2 (33.6% in Group1 vs. 53.8% in Group 2, p<0.001). In hospital MACE was 0.8% in Group 1 and 5.1% in Group 2 (p=0.089). Angiographic follow up at 8 month was performed in 53.2%. In-stent restenosis was detected in 5.9%. Clinical follow-up duration was 20.2짹11.8 months. Cumulative total MACE was 10.9% in Group 1 and 15.4% in Group 2 (p=0.089). TLR was 5.0% in Group 1 and 10.3% in Group 2(p=0.246). TVR was 7.6% in Group 1 and 12.8% in Group 2(p=0.316). Death was 2.5% in Group 1 and 2.6% in Group 2(p=0.988). MI was 0% in Group 1 and 5.1% in Group 2(p=0.013). And Stent thrombosis was 0.8% in Group 1 and 5.1% in Group 2(p=0.089). Conclusion Clinical outcomes of acute myocardial infarction of left circumflex artery as culprit between ST-elevation myocardial infarction and non ST-elevation myocardial infarction except myocardial infarction were not significantly different in this study. However, Group 2 tend to have higher mortality risk in hospital MACE and cumulative MACE. Therefore, large population study will be needed for better results. Key words : Acute myocardial infarction, Left circumflex artery, ST-segment change