This report is concerned to our experience of 10 cases of open heart surgery under the extracorporeal circulation at the Department of Thoracic and Cardiovascular Surgery, Capital Armed Forces General Hospital during the period between May, 1982 and February, 1983. 1. Six cases were male and two cases were female. Age was varied from 21 years to 50 years and mean age was 34 years. 2. The cases included 2 Ventricular Septal Defects, 1 Atrial Septal Defect, I Tetralogy of Fallot and 6 acquired valvular heart diseases. 3. The surgical managements were 3 primary repairs for Ventricular Septal Defects and Atrial Septal Defect, I total correction for Tetralogy of Fallot and 6 mitral valve replacements with bovine xenograft by Ionescu-Shiley combining 3 Tricuspid annuloplasties [ De Vega method ] and 1 deauricularization of left atrial appendage for acquired valvular heart diseases. 4. The average cardiopulmonary bypass time was 37 minutes for acyanotic congenital heart diseases and 92 minutes for cyanotic heart disease and acquired valvular heart diseases. And the average aortic cross clamping time was 19 minutes for the former and 70 minutes for the latter. 5. Postoperatively, there were 1 hemolytic anemia, 1 congestive heart failure, 1 hemolytic jaundice and 1 thermal burn as complications, but there was no operative mortality. 6. All patients received valve replacement were recommended anticoagulation with Persantin and Aspirin. [KTCS 1983;1:75-82]