Mitral valve prolapse (MVP) a common condition easily recognised by echocardiography with, however, strict criteria to avoid diagnosis by excess, may be complicated by arrhythmias. Two very different situations oppose severe decompensated mitral regurgitation due to myxoid dystrophy and quasi-asymptomatic MVP with a good prognosis and a low risk of complications. The important question is therefore to detect risk criteria of sudden death in patients with few symptoms. Unfortunately, no isolated factor or association of factors resolves this problem in a given patient. However, it is usually young women without severe mitral regurgitation but with thickened valves and, sometimes, a long QT interval, who are involved. Programmed ventricular stimulation and the detection of later ventricular potentials do not seem to be useful in the present state of our knowledge.