The early postoperative results for 10 patients who had Senning opeartion performed for transposition of the great arteries with intact ventricular septum were compared with the results for the most resent 11 patients who underwent Mustard operation. The averaged age and weight were not significantly different in the Senning or Mustard groups.(average 7.9 vs 7.7kg and 12.2 vs 12.5 months) In the Senning group, 8 patients underwent a modified Senning operation, including pedicled pericardial patch enlargement of the pulmonary venous pathway, and 2 patients underwent a Senning I operation. There were two hospital deaths with low cardiac output and one late death with congestive heart failure in the Mustard group, and no hospital and one late deaths with pulmonary venous obstruction in the Senning group. At the immediate postoperative period we found more stable hemodynamics, easier respiratory care and fewer transient arrythmias in the Senning than in the Mustard group. Eight patients in the Mustard group and three patients in the Senning group had immediate postoperative transient arrythmias, but all of the two groups were in regular sinus rhythm at the discharge. Postoperative catheterization was performed in eight patients of the each group and showed no systemic and pulmonary venous obstruction and normal corrected pacemaker recovery time in all patients.