Twenty-one cases of open mitral commissurotomy were done between October 1963 and March 1973. 1] Preoperative embolism consists of 7 cerebral and 2 peripheral cases. Two operative cerebral embolism cases were noted. 2] There were two cases of restenosis, one associated valvular disease, three mitral insufficiency cases, and six cases of pulmonary hypertension. 3] Out of 21 cases, 13 cases of atrial fibrillation were found and two cases of atrial fibrillation were found postoperatively among 8 cases of preoperatively normal sinus rhythm. 4] During operation 10 cases of valvular calcification and 6 cases of left atrial thrombus were noted. 5] Complete blood count, electrolyte and acid base balance showed normal range of data. 6] Four helix reservoir whole blood total body perfusion and 17 cases of .hemodilution perfusion utilizing Rygg-Kyvsgaard bag oxygenator with sigma motor were performed. 7] EACA 125 mg/kg intravenous administration before cardiopulmonary bypass resulted in markedly diminished postoperative bleeding. 8] Post-perfusion urine amount was in satisfactory range. 9] There were 2 operative mortality due to coronary embolism and three cases of hospital death, 2 due to severe hepatic failure and one due to cerebral embolism. 10] Sixteen survival cases showed marked clinical improvements and almost all of them returned to their occupation satisfactorily after operation.[KTCS 1973;1:69-88]