Background-The risks and benefits of long-term dual antiplatelet therapy remain unclear. Methods and Results-This prospective, multicenter, open-label, randomized comparison trial was conducted in 24 clinicalcenters in Korea. In total, 5045 patients who received drug-eluting stents and were free of major adverse cardiovascular events and major bleeding for at least 12 months after stent placement were enrolled between July 2007 and July 2011.Patients were randomized to receive aspirin alone (n=2514) or clopidogrel plus aspirin (n=2531 Continuing medical education (CME) credit is available for this article. Go to http://cme.ahajournals.org to take the quiz.