This paper presents our recent results of the Mustard procedure (intra-artrial baffle operation) for the complete transposition of the great arteries performed in 24 infants and children during the past 6 years at the Tohoku University Hospital. All intracardiac repairs were performed using "bypass hypothermia" (surface-induced deep hypothermia, circulatory arrest, and limited cardiopulmonary bypass). The hospital mortality rate was 8% in patients with simple transposition without pulmonary hypertension (Group I, one death in 12 patients), 50% in patients with ventricular septal defect (VSD) and pulmonary hypertension (Group II, 3 deaths in 6 patients), and 20% in patients with VSD and pulmonary stenosis (Group III, one death in 5 patients). Various types of longstanding dysrhythmia were found in 6 out of 18 long-term survivors, and subsequent pace-maker implantation was necessary in one infant. Postoperative pulmonary venous obstruction occurred in 3 infants, and surgical relief of the obstruction was successfully undertaken in 2 of them. Prevention of postoperative dysrhythmia, pulmonary venous obstruction, and possible brain damage are also discussed.