Neonatal arterial switch operation for simple dextro-transposition of the great arteries (d-TGA) has almost eliminated the occurrence of pulmonary vascular obstructive disease compared to patients who underwent Mustard or Senning procedure at an older age. We report a case of a neonate with d-TGA and intact ventricular septum who underwent arterial switch operation and yet developed severe pulmonary vascular obstructive disease within two months.