Background: Chronic kidney disease (CKD)is a strong risk factor for cardiovascular events, and there are consistence evidences about worse short- and long-term outcomes in CKD patients with acute myocardial infarction. The aim of this study was to evaluate the effects and safety of triple antiplatelet therapy (aspirin plus clopidogrel plus cilostazol) in CKD patients with ST-elevation myocardial infarction (STEMI) compared with dual antiplatelet therapy (aspirin plus clopidogrel). Methods: Among over 21,000 patients in Korean Acute Myocardial Infarction Registry (KAMIR) data, 5,138 STEMI patients who underwent successful primary PCI with drug-eluting stents were enrolled in this study. They were divided by estimated creatinine clearance (eCrCl) ��� 60 ml/min (n=3,445 dual = 2169, triple = 1276) and < 60 ml/min (n=1693 dual = 1120, triple = 573). Various major adverse cardiac events including major bleeding at 12 months were evaluated. Results: The triple group had significantly lower incidences of total death, cardiac death, and total major adverse cardiac eventsthan the dual group in both eCrCl groups. In group with eCrCl < 60 ml/min, triple therapy showed beneficial effect of 12-month total death in patients with older (���65) age, worse Killip class, and culprit lesion with left anterior descending artery. In group with eCrCl ��� 60 ml/min, triple therapy showed beneficial effect in patients with older (���65) age, and diabetes. But bleeding complications did not showed significant difference between the 2 groups in both eCrCl groups. Figure showed the cumulative incidences of all-cause mortality rates according to kidney function and antiplatelet strategies at 12 months. Conclusion: Triple therapy is a safe and effective antiplatelet strategy in CKD patients with STMEI.