To prevent postoperative pulmonary stenosis in arterial switch operation for transposition of the great arteries, pulmonary reconstruction without patch augmentation (modified Pacifico method: Pa-group) and reconstruction using W-shaped fresh autologous pericardium (AW-group) were introduced instead of the former method using equine pericardium (XW-group). Postoperative pulmonary stenosis (RV-PA pressure gradient greater than 30 mmHg) was not seen among the 17 cases in the Pa-group (0%), and was seen in 2/14 (14.3%) in the AW-group and in 4/14 (29%) in the XW-group. Progressive increase in pressure gradient was seen in the XW-group in the midterm cardiac catheterization (p < 0.01), but such tendency was not observed in the Pa-group and the AW-group. Sectional area at the pulmonary valve ring, at the anastomotic site in the main pulmonary artery, and at the pulmonary branches just distal to the bifurcation, standardized by the body surface area, increased in the Pa-group and the AW-group, but were unchanged or slightly decreased in the XW-group in the midterm cardiac angiography. We believe that postoperative pulmonary stenosis can be best avoided if modified Pacifico method is used. The cases in which postoperative pulmonary stenosis or coronary artery compression is anticipated such as those with side-by-side aortopulmonary relationship or after pulmonary artery banding, should be operated upon using fresh autologous pericardial patch.