Mitral valve prolapse shows a wide spectrum from a benign anatomic variant to a progressive disease with severe cardiovascular morbidity and mortality. Echocardiography is the most important tool for diagnosis and risk stratification. Predictors for high risk are significant thickening of mitral leaflet of > 5 mm ("classic" prolapse), moderate to severe mitral regurgitation and reduced left ventricular function. These patients have an increased risk of infective endocarditis, cerebral ischemia and sudden cardiac death. Because of the risk for the development of severe mitral regurgitation requiring surgery short follow-up intervals are necessary. In mitral prolapse syndrome cardiac clinical signs (palpitation, rhythm disorders, syncope, etc.) are associated with a prolapse that can be treated symptomatically with drugs after exclusion of other causes and significant mitral regurgitation requiring surgery.