Background: Although cilostazol reduced angiographic restenosis after bare-metal stent or drug-eluting stent (DES) implantation, its long-term clinical impact on the performance of DES has not been evaluated. Methods: This randomized, multicenter, prospective study compared triple antiplatelet therapy (aspirin, clopidogrel and cilostazol, triple group, n=250) and dual antiplatelet therapy (aspirin and clopidogrel, standard group, n=250) for 6 months in patients with long coronary lesions receiving DES. We evaluated long-term clinical outcomes (death, myocardial infarction, and target lesion revascularization) at 2 years. Results: Baseline clinical and angiographic characteristics were comparable between groups. At 2 years, the incidence of death (1.2% vs. 2.0%, p=0.724) and myocardial infarction (0.8% vs. 0.4%, p=0.999) was not statistically different between the two groups. However, triple therapy significantly reduced the 2-year target lesion revascularization compared to standard group (4.0% vs. 8.4%, p=0.041). Major adverse cardiac events including death, myocardial infarction, and target lesion revascularization was also significantly reduced in the triple than in the standard group (5.6% vs. 10.4%, p=0.048). During study period, 1 subacute stent thrombosis occurred in the triple therapy and 2 stent thromboses (1 late, 1 very late) in the standard group. Conclusions: Triple antiplatelet therapy after DES implantation is superior to in reducing 2-year risk of target lesion revascularization and major adverse cardiac events in long coronary lesions compared to dual antiplatelet therapy, which suggests that adding cilostazol on the dual antiplatelet regimen provides the improved efficacy of DES in lesions or patients at high risk of restenosis.