Objectives: To determine whether cilostazol would reduce intimal hyperplasia in patients undergoing long zotarolimus-eluting stent implantation (ZES) (stent length30 mm) for native long coronary lesions (length25 mm). Background: Restenosis after drug-eluting stent remains a significant clinical problem in long coronary lesions. Methods: Patients (n=499) were randomly assigned to triple (aspirin, clopidogrel and cilostazol, triple group, n=250) or dual antiplatelet therapy (aspirin and clopidogrel and placebo, dual group, n=249) for 8 months after long ZES implantation. The primary end point was in-stent late loss at 8–month angiography according to intention–to–treat principle. Results: The two groups had similar baseline characteristics. The in–stent (0.56짹0.55 mm vs. 0.68짹0.59 mm, p=0.045) and in-segment (0.32짹0.54 mm vs. 0.47짹0.54 mm, p=0.006) late loss were significantly lower in triple versus dual group, as were the 8-month in-stent restenosis (10.8% vs. 19.1%, p=0.016), in-segment restenosis (12.2% vs. 20.0%, p=0.028) and 12-month ischemic driven target lesion revascularization (TLR) (5.2% vs. 10.0%, p=0.042) rates. At 12 months, major adverse cardiac events (MACE) including death, myocardial infarction, and ischemic driven TLR was lower in triple than dual group (7.2% vs. 12.0%, p=0.066). Percent intimal hyperplasia volume by volumetric intravascular ultrasound analysis was reduced from 27.1짹13.2% for dual group to 22.1짹9.9% with triple group (p = 0.017). Conclusions: Patients receiving triple antiplatelet therapy after long ZES implantation had decreased extent of late luminal loss, percent intimal hyperplasia volume, and angiographic restenosis, resulting in reduced risk of 12-month TLR, compared to patients receiving dual antiplatelet therapy.