Between October 1968 and May 1985, 113 symptomatic pediatric patients (15 years or younger) had operation for rheumatic mitral stenosis or regurgitation. All were in functional classes III and IV of the New York Heart Association classification. The ages ranged from 5 to 15 years. There were 59 female and 50 male children. Nine patients also had grade 1 aortic regurgitation. Seventy-two children with moderately severe to severe mitral stenosis were treated with closed mitral commissurotomy. One patient with preoperative embolization had open commissurotomy while receiving cardiopulmonary bypass. There were two (2.7%) postoperative deaths. Sixty-one (83.5%) had excellent results, and 10 patients (13.7%) had good to fair results. Restenosis occurred in 14 patients (23.0%) over a 15-year period. Of the 40 patients with rheumatic mitral regurgitation, 36 had valve replacement, and mitral valve reconstruction was carried out in four. Six of these were in patients with mitral commissurotomy that was carried out 6, 8, 9, 10, 13, and 15 years earlier. There were four (10.0%) deaths during the postoperative period and one 8 months after operation resulting from a choked valve. Twenty-eight patients (80.0%) had excellent results and seven (20.0%) had fair to good results. Minor episodes of embolization occurred in three patients. All surviving patients were able to perform activities of daily living and showed a normal growth pattern. Three to 13 years' follow-up was available in 61 (85.9%) of 71 patients undergoing mitral commissurotomy who left the hospital and 27 (77.40%) in the mitral valve replacement/reconstruction group.