Fourteen neonates 18 hours to 32 days old with transposition of the great arteries (TGA) and virtually intact ventricular septum (IVS) underwent arterial switch operations under deep hypothermic circulatory arrest. Preoperative left ventricular to right ventricular peak systolic pressure ratios ranged from 0.7 to 1.0 (mean, 0.92), and the echocardiogram showed a centrally positioned ventricular septum in 10 patients and a rightward displaced ventricular septum in 4. One patient died twelve hours after operation. Postoperative complications included bleeding from the left coronary artery-pulmonary artery anastomosis (1 patient), stenosis of the pulmonary artery-aorta anastomosis requiring reoperation (2 patients), transient ST segment and T wave abnormalities consistent with ischemia (3), and development of pathological Q waves suggestive of clinically silent infarction (2). The capacity of the left ventricle in a neonate to effectively take over the systemic circulation was clearly demonstrated. A longer follow-up period is needed to assess late ventricular function, coronary ostial growth, growth of the aorta-pulmonary artery anastomosis, late aortic valve (anatomical pulmonary valve) function before definitive recommendations about the superiority of the arterial switch operation in neonates with TGA plus IVS can be formulated.