410 patients were operated upon by closed mitral commissurotomy in 1961-62. Of this group, 224 patients were followed up until 1978. The actuarial survival rate after 16 to 17 years postoperatively was 58%. Overall 43 patients were reoperated (second commissurotomy or mitral valve replacement). The cumulative reoperation rate of these patients was 1.5% per year. The mortality rate in patients with reoperation was 1.2% per year, without reoperation 2% per year. 87 patients are still alive 17 years after mitral commissurotomy without reoperation. 59% of this group belong to functional class II or I (NYHA). Most of them have combined mitral valve disease with predominant mitral stenosis. Atrial fibrillation was present in 33% (n = 29) preoperatively and in 58% (n = 50) postoperatively at the end of the study. Only 20% of all patients were on anticoagulant therapy. Nevertheless, the total embolic rate (5.7%) and the cumulative embolic rate (0.2% per year) remained low. The good long-term results show that mitral commissurotomy is an effective therapeutic approach in patients with mitral stenosis.