Over a 10 year period, 95 children aged 15 years and less underwent replacement of one or several of their heart valves, usually by a Starr-Edwards ball prosthesis. The predominant pathology was rheumatic heart disease and the most commonly affected valve was the mitral. Severe symptomatology, heart failure, cardiomegaly and high wedged-capillary and pulmonary arterial pressures were practically constant findings. Operative mortality was low (3.2%) and the long-term mortality was 10 patients. With an average follow-up of 40 months, results were excellent in the great majority of patients, with complete regression of symptoms, cardiomegaly and high capillary and pulmonary arterial pressures. Anticoagulant therapy was not systematic and only half the series were so treated. Thromboembolic complications were rare, 5.5% patients, but only affected those without anticoagulant therapy. The problems of evolving rheumatic disease and, above all, of tricuspid incompetence, the persistence of which after surgery on the mitral valve seems to be a sign of advanced myocardial damage, are discussed.