In briefHypertrophic cardiomyopathy brief (HCM) accounts for a large proportion of sudden deaths in young athletes. HCM is a complex disease with a broad clinical and morphologic spectrum. Most patients with HCM have impaired diastolic filling of the left ventricle, and about 25% have left ventricular outflow tract obstruction. Cardiac symptoms and/or signs are often present, and the condition is most effectively identified with echocardiography. Propranolol or verapamil relieves symptoms in many patients; surgery may benefit patients who have outflow obstruction associated with symptoms that persist after pharmacologic therapy. Patients with HCM should not engage in organized competitive sports or particularly strenuous exercise, although moderate recreational exercise is likely to be acceptable for such individuals.