18 adolescents and children who underwent mitral annuloplasty for severe mitral regurgitation were evaluated by echocardiography. In 7 patients studied preoperatively, mitral valve excursion ranged from 25 to 56 mm with E-F slopes from 92 to 160 mm/sec. 5 of the 7 patients showed mitral valve prolapse. The left ventricle was dilated in 6 and the left atrium was dilated in 4 patients. Postoperatively, the mitral valve excursion decreased (range 15–26 mm; p < 0.01) as did the E-F slope (range 44–100 mm/sec; 0.10 > p > 0.05). The prolapse pattern disappeared and the left heart chambers decreased in size. In these 7 patients and in 11 others studied postoperatively only, a common echocardiographic pattern was that of early anterior motion of the posterior mitral valve leaflet, which was not present preoperatively and was, therefore, tentatively ascribed to the technique of annuloplasty repair. No calcification and no definite mitral steosis has occurred in the follow-up of these patients to date. Persistent left atrial/left ventricular dilatation appeared related to residual mitral regurgitation with or without atrial fibrillation.