The aim of this study was to evaluate the technique of cerebral protection by selective cerebral perfusion with moderate hypothermia during surgery of the transverse aortic arch. Twenty-three patients were operated for partial or total replacement of the transverse aortic arch between January 1987 and December 1993 by the technique of selective cerebral perfusion by bilateral carotid cannulation. There were 12 cases of aneurysm of the ascending aorta and/or transverse aortic arch, one aneurysm of the innominate artery and 10 Stanford type A aortic dissections. The selective cerebral flow rate was 1-1.5 l/min; the perfusion pressure 60-80 mmHg and the temperature of cerebral perfusion 25-28 degrees C. The perioperative mortality was 13%; the causes of death were not neurological (3 haemorrhages). The neurological morbidity was 10% (one brachial monoparesis and one bulbar tetraparesis). This is therefore a useful technique of cerebral protection which avoids the complications of deep hypothermia with circulatory arrest and does not limit the time of aortic repair.