Obstructive sleep apnea (OSA) is the most common form of sleep-disordered breathing that is prevalent in the population and frequently under diagnosed. Usually presenting with respiratory symptoms, the most significant consequences of OSA are cardiovascular, including arrhythmias. The pathophysiology of OSA through multiple mechanisms may promote bradyarrhythmias, atrial fibrillation, premature ventricular complexes, ventricular arrhythmias, and sudden death. These mechanisms may acutely trigger nocturnal arrhythmias and may chronically affect electrical and structural myocardial changes, causing arrhythmias. Numerous epidemiological data have identified an increased risk for atrial fibrillation, ventricular fibrillation and sudden death in subjects with OSA. Diagnosis of OSA should be considered in patients with arrhythmias. However, not all patients with arrhythmias need to undergo formal testing for sleep apnea. Patients who are observed to have nocturnal arrhythmias should be considered for evaluation for possible OSA. Also, if the arrhythmia is refractory to standard therapy and if other clinical indicators of OSA are also present, there should be a low threshold for pursuing the diagnosis of sleep apnea. The principal therapy for OSA is continuous positive airway pressure (CPAP). Currently, there are limited data to support the efficacy of CPAP for arrhythmia prevention or treatment. Randomized trials are necessary to determine the efficacy of OSA treatment on arrhythmia prevention.