Unexpected findings of hyperamylasemia have been observed in patients with primary neurosurgical abnormalities without abdominal trauma or evidence of pancreatitis. However, the causes of hyperamylasemia in abovementioned cases have not been clearly elucidated. We have experienced hyperamylasemia in a 66 year-old female patient with subarachnoid hemorrhage caused by ruptured cerebral aneurysms who had had 2 aneurysms in right pericallosal and left middle cerebral trifurcational artery. Among the 2 aneurysms, the one in right pericallosal artery was ruptured and subarachnoid, intraventricular and intracranial hemorrhage was observed on the initial brain CT scan. There was no specific problem during operation and patient's staying in recovery room. Seven hours after the operation finished, severe hypotension and metabolic acidosis were occurred. Vital signs and acidosis were corrected with fluid and bicarbonate therapy. We incidentally found marked hyperamylasemia in the first postoperative day and serum amylase level was decreased and thereafter normalized through the seventh postoperative day. There was no evidence of acute pancreatitis on either clinical examination or radiologic study of abdominal sonography and CT scan. On the brain CT scan which was taken on the third postoperative day, the increase in the amount of hemorrhage in bilateral frontal area was found and cerebral ischemia was observed in the territory of bilateral anterior cerebral artery.