Nineteen patients with complete transposition of the great vessels were operated upon with use of the intra-atrial baffle (Mustard) technique. Eleven of the 19 survived and were discharged. Three late deaths occurred (total survival, 42.1%). Seventy percent of patients with an intact ventricular septum survived with one late death. Two of five patients with a ventricular septal defect survived the immediate postoperative period only to die after discharge. Postoperative complications were most often related to the respiratory system. Other complications included hemorrhagic diatheses, superior vena cava obstruction, arrhythmias, and wound infections. All patients discharged from the hospital were substantially improved clinically. Three late deaths occurred. Two sudden deaths were in children with postoperative arrhythmias. One was associated with pulmonary complications arising from the early postoperative period. Late cardiac catheterization (three patients) showed normal arterial oxygen saturation and decreased pulmonary ventricular systolic pressures. Mild pulmonary hypertension persists in two of these.