An 11 year old boy with a preductal coarctation and a patent ductus arteriosus underwent ligation of the ductus and patch aortoplasty for correction of the coarctation. His postoperative course was complicated by a paradoxical hypertension and a transient mesenteric arteritis syndrome which were successfully managed with sodium nitroprusside, propranolol and hydralazine. His urine catecholamine tests were markedly elevated one week after the operation which returned to normal 4 days later. Some of the salient points ~n the pathogenesis and management of these problems are discussed. [KTCS 1982;3:338-345]