Background; Recently major concerns emerged about the stent thrombosis after drug-eluting stent implantation that has been strongly associated with discontinuation of antiplatelet therapy. However the optimum duration of antiplatelet therapy is still investigated. The Endeavor stent elutes zotarolimus via a biocompatible polymer. This trial compared the safety and efficacy of short versus long-term Clopidogrel therapy after Endeavor deployment. Methods and Results; In 9 centers in Korea, 163 patients were enrolled for short term Clopidogrel therapy group that prescribes for 3 months, and 657 patients were reviewed for long term group that maintained for more than 6 months after Endeavor stenting from August 2006 to October 2007. After propensity score matching, 75 patients were remained in short term group and 225 patients in long term group. Baseline demographics and angiographic characteristics were not significantly different between two groups. There was no episode of stent thrombosis in two groups. There were no significant differences between short and long-term Clopidogrel therapy group in death (1.3% vs 0%, respectively; p=0.19), myocardial infarction (1.3% vs 1.3%, p=0.85), target lesion revascularization (6.3% vs 6.6%, p=0.07), and total MACE (7.8% vs 7.6%, p=0.05). In stent late lumen loss at 9 months were 0.45짹0.74 vs 0.54짹0.67mm (p=0.39). Conclusion; In addition to efficacy, this study strongly supports the safety of 3-month Clopidogrel maintenance after deployment of Endeavor stent. Longer follow-up in a larger patient cohort should be warranted.