In brief: Hypertrophic cardiomyopathy is the most common cause of sudden death in young conditioned athletes. The disorder is largely genetic, so families of patients need careful screening. Patients are often asymptomatic, but symptoms can include chest pain, near-syncope, palpitations, and dyspnea. A prominent S4gallop and a systolic murmur that is accentuated with standing and during Valsalva's maneuver suggest the diagnosis. Certain ECG, echocardiography, and cardiac catheterization features can help confirm the diagnosis. Athletes with hypertrophic cardiomyopathy should be restricted from vigorous exercise and treated with large doses of beta blockers. Antiarrhythmic agents are added, if necessary. Surgery is considered when large ventricular gradients are present and when symptoms do not respond to drug therapy.