From March 26, 1954, to July 19, 1955, 45 patients with major cardiac malformations not previously correctable underwent open repair utilizing cross-circulation between patient and donor without donor deaths. All operations were carried out at normothermia with lowered flow rates based on azygos flow studies. Twenty-seven patients, more than half of them infants, had ventricular septal defects closed. There were 8 hospital deaths, and there have been only 2 late deaths in 30 years. Fourteen (87.5%) of 16 who underwent recatheterization have closed defects. The 17 30-year-survivors are all in New York Heart Association Functional Class I. Five patients 4 months to 10 years old were operated on for atrioventricular canal (complete form). All had intractable failure, and 4 had pulmonary hypertension. Two of the 3 hospital deaths were due to heart block. The long-term survivor, a 15-month-old infant at the time of operation (severe pulmonary hypertension, 90/50 mm Hg), underwent repair 31 years ago and is now married with 3 children. Recatheterization disclosed normal pulmonary pressure (20/4 mm Hg), no shunts, and mild mitral regurgitation. Ten cyanotic tetrads 13 months to 14 years old were operated on with 5 hospital deaths. Of the 3 late deaths, 1 was accidental at 17 years, 1 occurred suddenly at home 13 years after operation in infancy for atresia, and the third occurred at reoperation 10 years later. The 2 remaining patients (1 the first patient operated on) are in excellent health. The surgical methods used and the physiological advantages of cross-circulation (temporary placenta) that made these results possible at a time when surgical knowledge was primitive are described.