The clinical presentation and operative results have been assessed of a series of patients with coarctation over the age of 40, and have been compared with a larger group of all ages.Long-standing hypertension increased markedly the incidence of symptoms due to left ventricular strain and cerebral hypertension. There was little increase in symptoms due to poor peripheral blood flow and no case of subacute bacterial endarteritis.The preoperative systolic blood pressures, when related to the normal for the age and sex of the patient, were higher and the diastolic pressures lower than an average group but signs of left ventricular strain were more common.At operation the aortic narrowing was found to be of usual severity. Grafts were necessary because of poor anastomotic tissue rather than long narrow segments as in the larger group. The operative mortality was doubled in the elderly, due entirely to hemorrhage from friable aortas. Morbidity was increased as a result of pulmonary and pleural complications.Postoperative blood pressures were almost exactly comparable with those of the over-all group when related to normal for age and sex. Symptoms were usually relieved but there was relatively slight radiologic or electrocardiographic change. The operative mortality and morbidity are acceptable in view of the risks of inaction and the satisfactory results of operation in the survivors.