OBJECTIVE The aim of this trial was to compare the safety and efficacy of paclitaxel-eluting stents (PES) and sirolimus-eluting stents (SES) for treatment of unprotected left main coronary artery (uLMCA) disease. BACKGROUND Both PES and SES have reduced the risk of restenosis, particularly in high-risk patient and lesion subsets. However, their comparative performance in uLMCA lesions is not known. METHODS In this randomized study, 607 patients with symptomatic coronary artery disease undergoing percutaneous coronary intervention for uLMCA were enrolled: 302 were assigned to receive a PES (Taxus, Boston Scientific, Natick, Massachusetts) and 305 assigned to receive a SES (Cypher, Cordis, Johnson & Johnson, New Brunswick, New Jersey). The primary end point was the combined incidence of death, myocardial infarction, and target lesion revascularization (TLR) at 1 year. The secondary end point was angiographic restenosis on the basis of the LMCA area analysis at follow-up angiography. RESULTS At 1 year the cumulative incidence of death, myocardial infarction, or TLR was 13.6% in the PES and 15.8% in the SES group (relative risk [RR]: 0.85, 95% confidence interval [CI]: 0.56 to 1.29, p = 0.44). One patient in the PES group (0.3%) and 2 patients in the SES group (0.7%) experienced definite stent thrombosis (p = 0.57). Mortality at 2 years was 10.7% in the PES and 8.7% in the SES group (RR: 1.14, 95% CI: 0.66 to 1.95, p = 0.64). Angiographic restenosis was 16.0% with PES and 19.4% with SES (RR: 0.82, 95% CI: 0.57 to 1.19, p = 0.30). CONCLUSIONS Implantation of either PES or SES in uLMCA lesions is safe and effective; both of these drug-eluting stents provide comparable clinical and angiographic outcomes. (Drug-Eluting-Stents for Unprotected Left Main Stem Disease [ISAR-LEFT-MAIN]; NCT00133237).