From 1975 to 1982, 31 infants were operated upon in the first year of life for aortic coarctation and congestive heart failure. Operations performed were resection and end-to-end anastomosis (RETE) in 14, subclavian flap aortoplasty (SFA) in six, patch aortoplasty (PA) in five, and other procedures in six. Thirty of the thirty-one (97%) survived the operation. To assess the effect of operation, 26 infants were studied noninvasively with Doppler arm-to-leg pressure measurements at rest and with stress. Preoperatively, the median arm-to-leg gradient at rest was 77 mm Hg. Serial postoperative Doppler studies demonstrated progressive changes in arm-to-leg pressure gradients: 69% had residual arm-to-leg gradients that spontaneously resolved, 13% had residual gradients that persisted, 13% had progressive increase in gradient, and one child had neither early nor late gradient. Stress testing often unmasked gradients not present in the resting state. No differences were noted among the three surgical groups: RETE, SFA, and PA. From our experience, we have made four conclusions with regard to repair of coarctation of the aorta in infants. First, surgical survival is expected. Second, the effect of the operation is dynamic, with four patterns defined: (1) complete relief of coarctation, (2) transient residual coarctation, (3) persistent residual coarctation, and (4) recurrent coarctation. Third, optimal surgical therapy seems to be an eclectic approach. Fourth, physiological evaluation of coarctation in infants can be obtained by Doppler techniques in conjunction with stress testing.