Background Although unprotected Left main coronary artery (LMCA) bifurcation lesion is a clinically and anatomically complex lesion, there are few data about outcome of the stent implantation in LMCA bifurcation lesion. We compared the clinical and angiographic outcomes of 1-stent versus 2-stent for the treatment of unprotected LMCA bifurcation lesion. Methods Patients with unprotected LMCA bifurcation lesion treated with provisional T-stenting technique using drug-eluting stent (DES) from March 2005 to October 2008 were included in this study. Patients with hemodynamic instability and who underwent primary percutaneous coronary intervention were excluded. Major adverse cardiac event (MACE) was defined as a composite of cardiac death, myocardial infarction (MI) or target lesion revascularization (TLR). Results Total 114 patients were included in this study (1-stent group n=59, 2-stent group n=55). In baseline characteristics, hypertension (p = 0.026) and true bifurcation lesion (p <0.001) was more frequent in 2-stent group. Minimal lumen diameter of side branch was significantly smaller in 2-stent group (p < 0.001). The procedural success rate was higher in the 1-stent group (98%) than in the 2-stent group (87%, p = 0.028). After a median follow-up of 587 days (range, 1-1520), the cumulative incidence of MACE was lower in 1-stent group than in 2-stent group but it was not statistically significant (10% vs 20%, p = 0.14). There was not the significant predictor of MACE in logistic regression analysis including hypertension, true bifurcation, procedural success rate and 2-stent technique. Angiographic follow-up at 9-month was available in 100 patients (88%). Angiographic restenosis rates were similar between the 2 groups (p = 0.65). Conclusion In our data, there was no difference in clinical and angiographic outcomes of 1-stent and 2-stent to treat unprotected LMCA bifurcation lesion.