The purpose of this investigation was to study exercise-induced hypertension after surgical repair of coarctation of the aorta (CoA). Groups of 27 patients with CoA and 27 healthy control subjects, 6-21 years old, were exercised to exhaustion using the Bruce protocol. Fourteen patients had undergone surgery during the first year of life (group A), and 13 patients had been operated on later (group B). The pulse rate and systolic blood pressures (BP) in the arm and leg were measured before, during, and after exercise to evaluate changes in the BP and the arm/leg BP gradient with exercise. The systolic BP was significantly higher in the patients than in the controls at all stages of the exercise test (p < 0.01), as was the arm/leg BP gradient both before and after exercise (p < 0.01); the latter increased significantly with exercise in the patient group (p < 0.05). We found hypertension to be a more common and severe problem in group B patients, who had higher blood pressures than their controls at rest and during exercise (p < 0.05). Exercise-induced hypertension was also more common in group B (23%) than in group A (7%). We conclude that exercise-induced hypertension and recoarctation are problems in postoperative CoA patients. Moreover, exercise-induced hypertension is more common in patients with CoA operated on after the first year of life.