To improve the surgical results of aneurysms of the transverse aortic arch, it is essential to select the optimal support technique to protect the cerebral ischemia during the aortic arch occlusion. In the four year period between 1983 and 1987, 21 consecutive patients had surgical correction of aneurysms of the transverse aortic arch at our institution. The causes of aneurysms were dissection (type A) in 16 patients and arteriosclerosis in 5 patients. Seven patients had emergency operation for frank or impending rupture. Two method for cerebral protection were employed during the period of arch exclusion. In Group I, 11 patients underwent selective cerebral perfusion both to innominate and left common carotid arteries via one roller pump at a rate of 600 ml/min (25 degrees C). The average cerebral perfusion time was 70.4 +/- 20.5 minutes. In Group II, 10 patients underwent deep hypothermia (15 degrees C to 20 degrees C) and total circulatory arrest to allow repair of the transverse aortic arch. The concomitant AVR was performed in two patients and CABG in one patient. The average cerebral arrest time was 35.2 +/- 3.4 minutes. Two out of 10 patients had additional cerebral perfusion because cerebral ischemic time exceeded over 45 minutes. There were three early deaths (14.3%) in this series. The causes of early death were bleeding in two patients and renal failure in one patient. There were no cerebral complications in both groups. The duration of extracorporeal bypass necessary for cooling and rewarming phase in Group II was longer than that in Group I.(ABSTRACT TRUNCATED AT 250 WORDS)