One case of surgical correction of a large aortopulmonary window in a 4 months old female is reported in detail. Clinical symptoms consisted of fatigue when feeding and recurrent upper respiratory tract infection. Under cardiopulmonary bypass with moderate hypothermia and cardioplegic arrest of the heart, the aortopulmonary window was approached through a vertical incision at the anterior wall of window itself. The defect was closed with pericardial patch using continuous suture posteriorly and sandwitch technique anteriorly. The patient was weaned from the cardiopulmoanry bypas without hemodynamic problem and postoperative course was uneventful. This surgical technique is recommandable as it provides good exposure of the defect and can be performed easily and safely.