Thirty patients over 40 years of age with atrial septal defects were operated on between 1981 and 1989. They were divided into two groups according to operative technique, group A of patients with direct suture of defect (17 cases) and group B patch closure (13 cases), in order to investigate the incidence of postoperative complications. Patient age and size of defect in group B were both greater than in group A. One group A patient had pulmonary stenosis, two group B patients had mitral valvular disease and six group B patients had pulmonary hypertension. The incidence of postoperative heart failure was 29% in group A and 61% in group B and that of arrhythmia was 47% and 69% respectively, however there were no intraoperative and postoperative deaths. We concluded that, although a high incidence of postoperative complications was observed in group B, patch closure was recommended for older patients with atrial septal defect because direct suture was more likely to distort the atrial septum.