Between 1977 and 1986, 38 children aged from 3.8 to 16.4 years underwent mitral valvuloplasty for symptomatic mitral valve incompetence of rheumatic origin. Two children (5.3 per cent) died in the immediate post-operative period, and 6 were lost sight of. Among the 30 children followed up for a mean period of 3.3 years, 6 were reoperated upon within 5 months of the valvuloplasty, 5 still present with a significant residual mitral valve incompetence and 9 have satisfactory clinical and echocardiographic results. Survival rate and survival rate without reoperation at 4 years were 93.8 per cent and 76.1 per cent respectively. Factors that correlated with the quality of long-term results were pre-operative left ventricular myocardial fibre shortening rate and surgical technique (poor results were obtained in children who had only one annuloplasty or none).