Echocardiographic findings satisfactorily compared with angiocardiographic data in six infants affected by congenital abnormalities of the mitral valve. Peculiar echocardiographic features were as follows: a) mitral stenosis: reduced E-F slope of the anterior mitral leaflet, paradoxical diastolic movement of the posterior leaflet, enlargement of the left atrium; b) "parachute mitral valve": small, dysmorphic, stiff mitral valve, with an extra echo projecting between those of the two leaflets; c) "cor triatriatum": enlarged left atrium whose cavity is divided in two portions by an extra echo; d) "hypoplastic left heart syndrome": the mitral leaflets are thin, short. The ventricular cavity and the diameter of the aorta are small; the right ventricle and the pulmonary artery are on the contrary markedly dilated.