Twenty eight patients with atrial septal defect operated on from May, 1983, to July, 1986 at the Department of Thoracic and Cardiovascular Surgery, Chungnam National University Hospital, were analyzed retrospectively. Among the 28 patients of atrial septal defect, 8 were male and 20 were female. Their ages ranged from 4.6 years to 52.5 years old with the mean of 15.3 years. The main clinical symptoms on admission were exertional dyspnea [82%], frequent respiratory infection [75%], palpitation [54%] and easy fatigability [25%]. Electrocardiographic findings were as follows: Regular sinus rhythm [100%], RVH [54%], RBBB [25%] and first degree of A-V block [4%]. Hemodynamic studies were performed in all cases and mean pulmonary systolic arterial pressure was 34.1*11.8mmHg. and mean Qp/Qs was 2.6*0.9. All 28 patients were operated under direct vision using extracorporeal circulation. 23 cases were secundum type defect and a single hole was found in 22 cases. The associated cardiovascular anomalies were found in 11 patients: ventricular septal defect in 3, patent ductus arteriosus in 1, partial anomalous pulmonary venous drainage in 2, mitral regurgitation in 2, tricuspid regurgitation in 1, anomalous left atrial septation in 1 and valvular pulmonary stenosis in 1. The defect closed directly in 22 cases and with patches in 6 cases. Postoperative complications were wound infection, arrhythmia bleeding, intracardiac patch detachment, pneumothorax and urethral injury. But there was no operative mortality.