BACKGROUND: Among drug-eluting stents released to date, the sirolimus-eluting stent has demonstrated the least amount of late lumen loss, but its efficacy and safety have not been compared head-to-head with the next-generation everolimus-eluting stent. METHODS AND RESULTS: The Scandinavian Organization for Randomized Trials with Clinical Outcome IV (SORT OUT IV) trial was a randomized multicenter, single-blind, all-comer, 2-arm, noninferiority trial comparing the everolimus-eluting stent with the sirolimus-eluting stent in patients with coronary artery disease. The primary end point was a composite of safety (cardiac death, myocardial infarction, definite stent thrombosis) and efficacy (target vessel revascularization) parameters. The noninferiority criterion was a risk difference of 0.015. Intention-to-treat analyses were done at 9- and 18-month follow-ups. A total of 1390 patients were assigned to receive the everolimus-eluting stent and 1384 patients to the sirolimus-eluting stent. At the 9-month follow-up, 68 patients (4.9%) treated with the everolimus-eluting stent compared with 72 patients (5.2%) treated with the sirolimus-eluting stent experienced the primary end point (hazard ratio, 0.94; 95% confidence interval, 0.67-1.31; P for noninferiority=0.01). At the 18-month follow-up, this differential remained: 99 patients (7.2%) treated with the everolimus-eluting stent versus 105 (7.6%) treated with the sirolimus-eluting stent (hazard ratio, 0.94; 95% confidence interval, 0.71-1.23). At the 9-month follow-up, the rate of definite stent thrombosis was higher in the sirolimus-eluting group (2 patients [0.1%] versus 9 patients [0.7%]; hazard ratio, 0.22; 95% confidence interval, 0.05-1.02). At the 18-month follow-up, this difference was sustained (3 patients [0.2%] versus 12 patients [0.9%]; hazard ratio, 0.25; 95% confidence interval, 0.07-0.88). CONCLUSION: The everolimus-eluting stent was found to be noninferior to the sirolimus-eluting stent. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00552877.