Coarctation of the aorta repair has been performed in 164 patients since July, 1947. Eighteen were younger than 6 mo. old; 44 were 1-11 yr; 87 were 11-40 yr; and 15 were older than 40 yr. Resection and end-to-end anastomosis were performed in 92; interposition grafts in 59; and other procedures in 13. Operative deaths occurred in 4 infants with multiple anomalies (22% infant mortality rate). Ten late deaths were due to associated anomalies (3), myocardial infarction (2), cerebrovascular accident (1), rupture of an aneurysm at the graft site (1) and unrelated causes (3). No hospital deaths occurred in patients with isolated coarctation or in patients older than 1 yr, including the 15 patients older than 40 yr. Late complications were evaluated in 147 patients followed from 2 mo.-28 yr. Restenosis occurred in 8 (3 repaired when younger than 6 mo.) and false aneurysm at graft sites in 2 (fatal rupture in 1). Residual hypertension occurred in 38 of 147 (25.9%) and was related to age at the time of repair: younger than 6 mo. (3 of 13), 1-11 yr (1 of 43), 11-40 yr (29 of 79) and older than 40 yr (5 of 13). Residual hemodynamic abnormality due to uncorrected associated anomalies, hypertension, ventricular hypertrophy, coronary artery disease, restenosis or anastomotic aneurysm occurred in 56.1% of 98 patients followed at least 2 yr. Of this group, 21.4% of those repaired before age 11 yr and 70% of those repaired after age 11 had residual hemodynamic abnormality. Hypertension and other residual hemodynamic abnormalities occur frequently after coarctation repair, but significantly less often when repair is performed between the ages of 1 and 11 yr. The incidence of mild hypertension is increased if repair is performed after 6 yr of age.