The long-term complications of patch plasty repair for coarctation of the aorta were assessed retrospectively in 119 patients who were operated upon from 4 days to 13 years of age. There were 7 late deaths and 17 patients were lost to follow-up. Thus 95 patients were followed up for a minimum period of 3 years (mean 6.3 years). In addition, graded exercise tests were performed on 15 patients and 11 normal controls, measuring systolic blood pressure response and arm-leg blood pressure gradients. In this series, 16 patients (17%) were hypertensive, while 25 (26%) had a resting systolic arm-leg gradient greater than 20 mm Hg. Re-coarctation occurred more frequently when surgery had been undertaken under 1 month of age. Review of chest X-rays revealed calcification in the patch in 4 patients, one of whom subsequently went on to aneurysm formation. In a second child aneurysm formation was detected at repeat operation. Exercise tests showed a significantly higher systolic arm pressure in patients (mean: 165.3 mm Hg) when compared to controls (mean: 139.2 mm Hg) (P = 0.017) and a significant increase in arm-leg systolic gradient viz. 36 and 5.9 mm Hg, respectively (P = 0.0016). A good correlation was found between the systolic arm pressure and the systolic arm-leg gradient after exercise (r = 0.822; P = 0.0001). We conclude that the most important long-term complication following an aortic patch plasty, is re-stenosis. The development of an aneurysm was observed only twice. We believe that this apparently rare occurrence, as assessed on chest radiographs; is related to the young age (53% under 1 year) at which the repairs were carried out. Another possible reason may be that the follow-up period is not yet long enough.