Background: In our previous COREA-TAXUS randomized trial (Lancet 2007), the 6 months��� adjunctive use of celecoxib that is inhibitor of proliferation promoting gene, akt, as well as cyclo-oxygenase-2, reduced the need for revascularization of the target lesion without increased thrombotic risk. We aimed to test the efficacy and safety of 3-month use of celecoxib in patients receiving drug eluting stent (DES) implantation in the ���larger��� prospective randomized multicenter trial. Methods: We enrolled and randomized 896 patients who had angina pectoris or a positive stress test due to the native coronary artery lesions for which implantation of drug-eluting stents was feasible. Patients were randomized into control or celecoxib group with stratification by stents: paclitaxel-eluting stent (PES) and zotarolimus-eluting stent (ZES). In the celecoxib group, 200mg of celecoxib was given twice daily for 3 months after the revascularization. The primary endpoint was late luminal loss on quantitative coronary angiography at 6 months after the intervention. Results: Baseline demographic and angiographic characteristics were similar between groups. In-stent late luminal loss was significantly lower in the celecoxib group than the control group (p<0.05). Similar trends were observed in both ZES group and PES group. Celecoxib treatment reduced the clinically-driven target lesion revascularization compared to the control. But it did not reduce major adverse cardiac event (composite of cardiac death, non-fatal myocardial infarction, and the target lesion revascularization (p>0.05). Thrombotic risk of celecoxib was observed in patients receiving dual antiplatelet therapy with aspirin and clopidogrel but not in patients receiving triple antiplatelet therapy with aspirin, clopidogrel and cilostazole. Verifynow P2Y12 reaction unit was higher in celecoxib group in the dual antiplatelet group, but not in triple antiplatelet group. Conclusion: Adjunctive use of celecoxib for 3 months would be useful to reduce late luminal loss of DES. However, thrombotic risk of celecoxib needs further evaulation.