Two hundred forty-five patients less than 15 days of age with transposition of the great arteries with or without a ventricular septal defect or pulmonary stenosis were entered into an ongoing 20 institution treatment study between January 1, 1985 and June 1, 1986. Complete follow-up is available on all patients. The ventricular septal defect narrowed in only 1 of 36 patients with combined transposition of the great arteries and ventricular septal defect; pulmonary stenosis developed or worsened in 3 of these 36 patients and in 3 of the 187 patients with simple transposition. Twelve month overall survival among the 245 patients was 80%. No morphologic feature of transposition was a risk factor for death but major associated cardiac and noncardiac anomalies (more common in patients with combined transposition and ventricular septal defect) and low birth weight were risk factors. Neither arterial switch repair (n = 86), atrial switch (Mustard) repair (n = 21) nor atrial switch (Senning) repair (n = 39) was a risk factor for death, but results in all surgical groups were better in the last part of the experience. Death before repair was less frequent late in the study. Possibly, in low birth weight infants, survival was better with the arterial than with the atrial switch repair. These data suggest that survival at 1 year is similar with either the arterial or the atrial switch repair. The early results of repair of combined transposition of the great arteries and ventricular septal defect are as good as those of simple transposition. Special institutional efforts are required to attain good results with the arterial switch repair and to prevent death before repair.