From 1981 to 1992, 10 infants with aortopulmonary septal defect (APSD) underwent surgical repair. The mean age at operation was 5.6 +/- 5.5 months, and the mean weight 4.6 +/- 2 kg. Intracardiac associated anomalies were as follows: ventricular septal defects (7 cases), tetralogy of Fallot (2 cases), aortic valve stenosis (2 cases), atrial septal defect (3 cases), patent ductus arteriosus (3 cases), pulmonary valve stenosis (1 case). Cardiac catheterization was performed in 8 out of 10 patients. Eight patients had type I (proximal) defect, 1 had type II (distal) defect and 1 had type III (absent aortopulmonary septation) defect. A variety of surgical procedure was employed. APSD closure with hemoclip was feasible in 3 cases with small window. In 6 patients, during a period of cardiopulmonary by-pass, a side biting clamp was positioned on the ascending aorta close the defect; the border of the window was divided leaving a flap of pulmonary wall on the left side to close the aortic defect; the pulmonary artery was repaired by an autologous pericardial patch. In the patient with type III APSD, aortopulmonary septation was carried out through a transwindow approach. Associated anomalies were repaired in all infants except one. Hospital mortality was 10% (1 case). No late deaths occurred. At a mean follow-up of 47 +/- 35 months 8 patients are asymptomatic and 1 is awaiting for repair of associated anomalies. Conclusions. APSD is a rare but nonetheless well identifiable anomaly. Surgery is indicated as soon as the diagnosis is established, regardless of the patient's age.(ABSTRACT TRUNCATED AT 250 WORDS)