Sixty-eight patch aortoplasties were performed for coarctation of the aorta (CoA) in adult patients from 1967 to 1978 in our hospital. The mortality was 1.5% and the immediate result of the surgical repair seemed good. Long-term follow-up of 2 to 14 years later revealed aneurysm formation at the repair area in 27% of the 62 patients for whom sufficient follow-up data are available. Two aneurysms had ruptured with a fatal outcome. Other repair methods used for coarctation in 106 patients were free from aneurysm complication. Thirteen patients with an aneurysm underwent reoperation without mortality. The etiology of these unexpected aneurysms is discussed.