Pulmonary atresia with ventricular septal defect (VSD) and severe hypoplasia of the pulmonary branches is a serious malformation and reputedly inoperable. The surgical restoration of a pulmonary outflow tract may nevertheless dilate the pulmonary arterial branches in the long term. The probable mechanism of this effect is related to high right ventricular and pulmonary pulse pressures due to the absence of the pulmonary valve. The right to left shunt, initially, reverses after a few weeks so authorizing closure of the VSD. Two patients, an adult and a child, were successfully treated by this technique.