We experienced a case of surgery for ruptured aneurysm of the aortic arch. A 51-year-old man who had been admitted complaining of back pain was diagnosed as ruptured aortic arch aneurysm by chest X-ray film and computed tomography. The aortic arch and descending aorta was replaced with a Dacron graft under profound hypothermic selective cerebral perfusion (PHSCP). The post operative course was well without neurological complications. Since 1982 we have utilized PHSCP in four cases of thoracic aortic aneurysms including this case. The average of PHSCP time was 143 minutes. Perfusion rate of carotid arteries was 400-800 ml/min during PHSCP. The average of lowest blood temperature was 15.5 degrees C. It was suggested that PHSCP was a safe and effective method for surgical treatment of thoracic aortic aneurysms.