A total of 18 open mitral commissurotomy were performed at Seoul National University Hospital between January 1975 and August 19. Thirteen patients had open mitral commissurotomy alone and five had additional cardiac procedure. Six patients were men and twelve were women. The mean age was 33 years. According to the NYHA classification, the distribution of patients preoperatively was as follows; Glass II, 2 patients; class III, 14 patients; class IV, 2 patients. Three patients had emboli preoperatively, all of whom were in atrlal fibrillation. There was no operative death. The patients were followed from 2 to 86 months [mean 26 months]. There was no late death and no embolic episode. Mitral valve replacement was required in one patient due to mitral restenosis after 4 years. [KTCS 1982;4:387-393]