Seventy-six patients were studied after arterial switch operation (ASO) between May 1977 and February 1992. Pulmonary artery reconstruction was initially performed by: conduit interposition in 5 patients, direct main pulmonary artery anastomosis and button patches in 60 patients, and pantaloon-like patch repair in 11 patients. Pulmonary stenosis developed in 17 patients (22%), requiring a total of 26 late re-interventions. Re-intervention was required in four out of five patients operated with pulmonary artery conduits, 11 out of 60 with a button patch repair and 2 out of 11 following pantaloon-type repair. In this series pulmonary artery stenosis (PS) involving the pulmonary valve occurred in 9/17 patients. Involvement of the pulmonary valve was related to the technique of pulmonary artery reconstruction. In these patients surgery is necessary. Balloon angioplasty can be a valuable tool when the stenosis is more distal. The incidence of PS was not influenced by the type of reconstruction or the use of Lecompte's maneuver.