45 children with echocardiographically proven mitral valve prolapse are the basis to give a review about this syndrome (MVPS). Symptoms in this syndrome, like palpitations and fatigue are rare. Only half of the patients show the typical auscultatory findings: the midsystolic click and the late systolic murmur. The ECG abnormalities are disturbances of rhythm, left ventricular hypertrophy and left ventricular T-wave inversion. The hemodynamic is mostly normal or depends upon the degree of the mitral insufficiency. The angiocardiograms show often abnormalities of the contraction of the left ventricle. Echocardiographically one ought to obtain the pattern of the mid-systolic backward motion of the leaflet. As additional lesions we found in 11% of the patients with MVPS an ASD, in 16% an ASH or IHSS of different degrees corresponding to the echocardiographical sign of the ASH. The pathogenetic ideas of the valvular and myocardial theory are discussed. The prognosis is good. Complications are disturbances of rhythm, bacterial endocarditis and in case of a chordal rupture a mitral regurgitation.