From June, 1975, through April, 1986, 11 consecutive infants with aortopulmonary window were operated on at the Department of Cardiac Surgery, Ospedali Riuniti, Bergamo, Italy. The classic type of aortopulmonary window was present in 6 patients, whereas 4 patients had a ductus type of aortopulmonary window and 1 patient had a double aortopulmonary window, associated transposition of the great arteries, and ventricular septal defect. Operative technique included patch closure of the defect by means of cardiopulmonary bypass using various approaches: transaortic in 3, transpulmonary in 2, and transwindow in 2. The aortopulmonary window was ligated in 3 patients, in 2 of whom an incorrect diagnosis of patent ductus arteriosus was made at cardiac catheterization. Division and suture of the defect through a median sternotomy was performed in the remaining patient, who was moribund on admission. There was a single operative death. All survivors are in New York Heart Association Functional Class I at a mean interval of 6 1/2 years postoperatively.