Background and Objectives : Percutaneous coronary intervention (PCI) of unprotected left main coronary artery (LMCA) stenosis showing promising outcomes in drug-eluting stent era. However, data are lacking as to the long-term outcomes according to lesion complexity and location. The aim of this study is to evaluate clinical and angiographical outcomes in long term after implantation of sirolimus eluting stent (SES). Materials and Methods : From July 2003 to August 2005, eighty four consecutive patients who underwent attempted SES stent implantion at three centers were enrolled in this study. The patients were divided into two groups according to the lesion location. Group 1 (n=39) was defined as patients had a significant stenosis in ostium and/or body. Group 2 (n=45) was defined as patients had a left main coronary lesion involving bifurcation. Stenting techniques were used at the discretion of the operator���s decision according to the characteristics of the lesion location. The composite major cardiac events (MACE) of death, myocardial infarction and revascularization were evaluated at the index hospitalization, at 1 year and 2 years. Results : Baseline characteristics between two groups were not statistically different. Only stent cross-over technique was used in all cases of Group 1. Complex stenting techniques such as kissing, T stenting and Crush techniques were used in 25 patients of Group 2 (p=0.001). Periprocedural and in-hospital MACE was not significantly different between two groups. Two in-hospital deaths due to cardiogenic shock and acute stent thrombosis were occurred in group 2. During the follow up MACE was higher in group 2 at 1 year (2.6 % vs 22 %, p=0.007) and at 2 year (2.6 % vs 22 %, p=0.0070) ). Stent thrombosis (ST) occurred in 1 patients (2.2%) of Group 2; 1 subacute ST and 1 patients (2.6%) of Group 1; 1 late ST. Angiographic follow up showed 9 restenosis (10.7 %) at LCX ostium (n=7) and main body (n=2) in only group 2 (p=0.013). Conclusion : PCI using SES in LMCA lesion showed favorable short and long term outcomes in selected patients. Also, lesion location is an important factor for the clinical and angiographical outcomes.