From Oct. 1983 to Dec. 1991, 135 cases of atrial septal defect which were operated at the department of Thoracic and Cardiovascualr Surgery, Chonnam National University Hospital, were analysed retrospectively. They were 23.7% of all congenital heart diseases operated in the same period. Among the 135 cases, 62 cases were male and 73 cases were female. Their ages were ranged from 2 to 54 years and the mean was 18 years old. Main symptoms at admission were exertional dyspnea[70.37%], frequent URI[49.12%] and palpitation[32.59%], but 12 cases[8.88%] were asymptomatic. Electrocardiographic findings wer regular sinus rhythm in 96.99%, RVH in 64.66%, incomplete RBBB in 27.06%, complete RBBB in 42.10%, and first degree AV block in 9.02% All 135 cases were operated under the direct vision with cardiopulmonary bypass. Anatomically, most frequent type was fossa ovalis defect with complete septal rim[78.52%]. 117 of 135 ASD patients were repaired with pathch closure[86.66%] and 14 patients were repaired with direct closure[10.37%] and 4 patients in mutiple ASD were repaired with patch and direct closure[2.96%]. Postoperative complications were occured in 21 cases[15.56%], and they were wound infection, pleural effusion, postoperative bleeding, urinary tract infection, and heart failure mainly. One case died due to epidural hematoma and operative mortality was 0.74%.