In briefIn most people, mitral valve prolapse, which affects women more than men, is a benign condition with few or no symptoms. But in some patients it poses a significant problem. Potential sequelae include endocarditis, serious arrhythmia, and sudden death. Although a midsystolic click followed by a late systolic murmur is characteristic, definitive diagnosis requires echocardiography. Treatment ranges from education and reassurance in those who have mild disease to valve replacement in severe cases. Most athletes who have mitral valve prolapse can safely participate in all activities. Those with evidence of significant valvular disease, serious arrhythmia, or a family history of sudden death due to mitral valve prolapse, however, should participate only in low-intensity competitive sports.