Nontraumatic, incracranial giant aneurysm has rarely been reported as the cause of the spontaneous subarachnoid hemorrhage in childhood. Multiple, dissecting giant aneurysms on the left middle cerebral artery with sudden onset of headache in a 14-year-old girl were successfully clipped and followed by complete relief of symptoms. The rarity and characteristics of such lesion in childhood and its successful surgical treatment are discussed briefly.