Stroke is a major complication of surgical aortic valve replacement (SAVR). OBJECTIVE: To determine the efficacy and adverse effects of cerebral embolic protection devices in reducing ischemic central nervous system (CNS) injury during SAVR. DESIGN, SETTING, AND PARTICIPANTS: A randomized clinical trial of patients with calcific aortic stenosis undergoing SAVR at 18 North American centers between March 2015 and July 2016. The end of follow-up was December 2016. INTERVENTIONS: Use of 1 of 2 cerebral embolic protection devices (n = 118 for suction-based extraction and n = 133 for intra-aortic filtration device) vs a standard aortic cannula (control; n = 132) at the time of SAVR. MAIN OUTCOMES AND MEASURES: The primary end point was freedom from clinical or radiographic CNS infarction at 7 days (± 3 days) after the procedure. Secondary end points included a composite of mortality, clinical ischemic stroke, and acute kidney injury within 30 days after surgery; delirium; mortality; serious adverse events; and neurocognition. RESULTS: Among 383 randomized patients (mean age, 73.9 years; 38.4% women; 368 [96.1%] completed the trial), the rate of freedom from CNS infarction at 7 days was 32.0% with suction-based extraction vs 33.3% with control (between-group difference, −1.3%; 95% CI, −13.8% to 11.2%) and 25.6% with intra-aortic filtration vs 32.4% with control (between-group difference, −6.9%; 95% CI, −17.9% to 4.2%). The 30-day composite end point was not significantly different between suction-based extraction and control (21.4% vs 24.2%, respectively; between-group difference, −2.8% [95% CI, −13.5% to 7.9%]) nor between intra-aortic filtration and control (33.3% vs 23.7%; between-group difference, 9.7% [95% CI, −1.2% to 20.5%] ). There were no significant differences in mortality (3.4% for suction-based extraction vs 1.7% for control; and 2.3% for intra-aortic filtration vs 1.5% for control) or clinical stroke (5.1% for suction-based extraction vs 5.8% for control; and 8.3% for intra-aortic filtration vs 6.1% for control). Delirium at postoperative day 7 was 6.3% for suction-based extraction vs 15.3% for control (between-group difference, −9.1%; 95% CI, −17.1% to −1.0%) and 8.1% for intra-aortic filtration vs 15.6% for control (between-group difference, −7.4%; 95% CI, −15.5% to 0.6%). Mortality and overall serious adverse events at 90 days were not significantly different across groups. Patients in the intra-aortic filtration group vs patients in the control group experienced significantly more acute kidney injury events (14 vs 4, respectively; P = .02) and cardiac arrhythmias (57 vs 30; P = .004). CONCLUSIONS AND RELEVANCE: Among patients undergoing SAVR, cerebral embolic protection devices compared with a standard aortic cannula did not significantly reduce the risk of CNS infarction at 7 days. Potential benefits for reduction in delirium, cognition, and symptomatic stroke merit larger trials with longer follow-up. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT02389894.