In an athletic population, the incidence of palpitations varies from 0.3% to as high as 70%, depending on age and type of sport being studied. Palpitations, or an awareness of an increased or abnormal heart beat, are rare in the school-age athlete, but much more common in older endurance athletes. The majority are felt to be benign, with prognosis relating to type of specific rhythm disturbance and presence or absence of underlying heart disease. Atrial fibrillation can account for up to 9% of rhythm disturbances in elite athletes, and up to 40% in those with long-standing symptoms. In athletes with premature ventricular beats (PVCs), underlying heart disease is more likely to be present in those with a high PVC burden, defined as >/=2000 PVCs/24 hours. Choice of monitoring device is crucial in making a proper diagnosis of the specific rhythm disturbance. For symptoms occurring within a 24-hour period, simple Holter monitoring is adequate to make a diagnosis. However, if symptoms occur less frequently, clinicians must choose one of the other available monitoring devices. Most importantly, choice of device should depend on which device is most likely to detect the rhythm disturbance. Other cardiac testing such as echocardiography, stress testing, endomyocardial biopsy, genetic testing, electrophysiologic testing, or cardiac magnetic resonance imaging may be indicated as well. The majority of palpitations in athletes will be first identified by screening examination, or by a complaint from the athlete. The third and most current pre-participation examination monograph recommends asking the athlete if he/she has palpitations with exercise. The assumption has been made that palpitations occurring at rest in athletes are benign, but this theory has not been validated prospectively in a large cohort of the athletic population. Specific rhythms can often be treated with radiofrequency ablation, with return to sports provided there is no significant high risk underlying heart disease present. Athletes with known malignant ventricular rhythm disturbances, or underlying substrate for such, who have undergone implantation of an automatic implanted cardioverter-defibrillator are not recommended to return to sport because there is no data on the safety and efficacy of defibrillators in this clinical setting, and certain athletic activities may result in damage to the device.