Abstract： Background Cilostazol is a newly developed antiplatelet drug that has been widely applied for clinical use. Its antiplatelet action appears to be mainly related to inhibition of intracellular phosphodiesterase activity. Recently,cilostazol has been used for antiplatelet therapy after coronary bare metal stent implantation for thrombosis and restenosis prevention. This prospective randomized and double blind trial was designed to investigate the safety and efficacy of cilostazol for the prevention of late restenosis and acute or subacute stent thrombosis.Methods One hundred and twenty patients who underwent elective stent were randomly assigned to treatment group with cilostazol 200 mg/d (n = 60), clopidogrel 75 mg/d and aspirin 100 mg/d or to control group with clopidogrel treatment 75 mg/d (n = 60) and aspirin 100 mg/d. Follow-up coronary angiography was performed 6-9 months later.Results Nine months major adverse cardio-cerebral event (MACCE) were lower in treatment groups (P＜0.05).The quantitative coronary angiography (QCA) at 6 months follow-up showed that minimum lumen diameter(MLD) was higher in treatment group than that of control group [(2.14±0.52)mm vs (1.82 ±0.36)mm, P＜0.05].Late lumen loss (LL) [(0.82 ± 0.42)mm vs (1.31 ± 0.58)mm; P＜0.01 ], restenosis rate (RR) (14% vs 32%; P＜0.05)and target lesion revascularizaion (TLR) rate (5% vs 17%; P＜0.05) were lower in treatment group than in control group.Conclusion Cilostazol therapy is an effective regimen for prevention not only stent thrombosis but also RR and TLR through reducing MLD without the risk of increasing bleeding.