We studied the mode of presentation and results of surgery in 45 adults with coarctation of the aorta. Coarctation was unsuspected in 23 patients, 3 of whom presented with acute aortic dissection and 4 with severe aortic valve disease. Twenty seven were hypertensive before surgery. Three patients required emergency operation and all died. There was one death and one postoperative paraplegia amongst 39 patients who underwent elective operation. Of 21 preoperatively hypertensive patients studied at least 2 years after surgery blood pressure returned to normal levels in 10. Acute aortic dissection, aortic aneurysm formation and aortic valve disease complicate the surgical treatment of adult coarctation and hypertension may persist in as many as 50% of patients. Nevertheless surgery is preferable to the poor reported results of long term medical management.