Background: Some studies have shown that left main (LM) intervention with preserved left ventricular (LV) function is feasible and safe. The aim of this study was to evaluate the safety and efficacy of drug-eluting stent (DES) implantation in LM or its bifurcation lesion regardless of LV dysfunction up to 6 months. Methods: All patients (pts) with unprotected LM regardless of LV dysfunction were electively treated with either sirolimus-eluting stent (SES; Cypher) or paclitaxel-eluting stent (PES; Taxus). LM bifurcation lesions were treated by kissing stenting, crushing technique or stent crossover (Stent/Balloon). All pts received aspirin, clopidogrel (300-600 mg) and cilostazol as the triple antiplatelet regimen and unfractionated heparin (UFH; 50 IU/Kg) was given during the PCI. Early and mid-term clinical and angiographic outcomes were investigated. Results: A total 22 pts (Male 13, mean age, 59.8 짹 10.5 years) who underwent standard PCI with DES on unprotected LM lesion were enrolled. Eight pts (8/22, 36.4%) had LV dysfunction (moderate in 3 pts, mean EF=25% function, mild in 5 pts, mean EF=48%). Target lesions were 14 LM bifurcations, 5 LM ostial, 3 LM body to LAD lesions. Ninety two percent (12/13) of bifurcation lesions were treated by kissing stenting technique. Seven pts (7/22, 31.8%) were treated by PES and 15 pts (15/22, 68.2%) by SES. A total 36 DESs (26-Cypher, 10-Taxus) were utilized to treat 36 lesions. Mean DES diameter was 3.06 mm and length was 22.4 mm in bifurcation lesions. Five pts (5/22, 68.2%) needed inotropic support during the PCI. Only one pt with acute myocardial infarction (MI, EF 50%) had acute stent thrombosis in non-target lesion. At 6 months, only one pt showed angiographic binary restenosis (type II) and there were no additional in-hospital target lesion and vessel revascularization, Q-wave MI, major adverse cardiac events and deaths and these benefits were well maintained up to 6 months. Conclusion: Despite the expected higher risk of LM disease, DES implantation in unprotected LM regardless of LV dysfunction appears safe and associated with low angiographic restenosis and favorable clinical outcomes up to 6 months.