In patients with kidney failure, i.e., chronic kidney disease in stages G5 and G5D, who are undergoing chronic kidney replacement therapy, the prevalence and incidence of arrhythmic disease is extremely high. Several factors contribute to this phenomenon; some are common to the general population, while others are specific to kidney disease and kidney replacement therapy (i.e., dialysis). The two major arrhythmic conditions present in patients with kidney failure, which are a major cause of morbidity and mortality in this population, are atrial fibrillation and sudden cardiac death. This chapter will discuss the epidemiology and pathophysiology of these arrhythmias, as well as the issues related to their prevention and treatment in this high-risk population.