Despite the importance of cardiovascular disease in dialysis patients, the frequency of atrial fibrillation in incident dialysis patients has not been determined. We analyzed the prevalence of atrial fibrillation in patients starting dialysis over a 4-year period, its occurrence over the course of dialysis, and its influence on ischemic stroke and mortality. Factors predisposing to atrial fibrillation were noted, as was the influence of arrhythmia on mortality and presentation of ischemic stroke. Of the 256 patients studied, 31 had atrial fibrillation at the start of dialysis. Increased age, larger left atrium, and female gender were independently related to the presence of atrial fibrillation at dialysis inception. Of the 225 patients who were in sinus rhythm at the start of dialysis, 28 developed atrial fibrillation during a mean follow-up time of 2 years. The presence of valvular calcifications, bundle branch block, previous ischemic stroke, lower ejection fraction, higher pulse pressure, and lower hemoglobin concentration were predictors of the clinical evolution of atrial fibrillation. Overall, atrial fibrillation increased mortality risk 1.72-fold and ischemic stroke risk 9.8-fold. Therefore, it appears that atrial fibrillation is quite prevalent and its presence is associated with significant risk.