Enlarged bronchial arteries and/or systemic-to-pulmonary collaterals have been frequently demonstrated in association with transposition of the great arteries. They are usually clinically silent, although they might be large enough to cause accelerated pulmonary vascular obstructive disease or symptomatic cardiac volume overload after surgical repair. We report on a low-weight neonate with transposition of the great arteries and intact ventricular septum who showed a stormy postoperative course because of multiple aorto-pulmonary collaterals early after a successful arterial switch operation. Percutaneous coil embolization of these anomalous vessels resulted in sudden weaning from mechanical ventilation and hospital discharge in a few weeks.