Whether oral anticoagulant use should be considered in patients undergoing hemodialysis with atrial fibrillation (AF) remains controversial because of the uncertainty regarding risk-benefit assessments. The purpose of this study was to investigate the risk of ischemic stroke in patients undergoing hemodialysis with new-onset AF, in comparison with those without arrhythmia. Methods and Results-This nationwide, population-based, propensity score-matched cohort study used data from Taiwan's National Health Insurance Research Database during 1998 to 2011 for patients on hemodialysis with new-onset nonvalvular AF and matched subjects without arrhythmia. The clinical end points were ischemic stroke (fatal or nonfatal), all-cause death, and other serious adverse cardiovascular events. In comparison with the matched cohort, patients with AF (n=6772) had higher risks of ischemic stroke (adjusted hazard ratio [aHR], 1.27; 95% confidence interval [CI], 1.13-1.43), all-cause death (aHR, 1.59; 95% CI, 1.52-1.67), in-hospital cardiovascular death (aHR, 1.83; 95% CI, 1.71-1.94), myocardial infarction (aHR, 1.33; 95% CI, 1.17-1.51), and hospitalization for heart failure (aHR, 1.90; 95% CI, 1.76-2.05). After considering in-hospital death as a competing risk, AF significantly increased the risk of heart failure (HR, 1.56; 95% CI, 1.45-1.68), but not those of ischemic stroke and myocardial infarction. Additionally, the predictive value of the CHA2DS2-VASc score for ischemic stroke was diminished in the competing-risk model. Conclusions-The risk of stroke was only modestly higher in patients undergoing hemodialysis with new-onset AF than in those without AF, and it became insignificant when accounting for the competing risk of in-hospital death.