PURPOSE: The occurrence of traumatic aneurysm is rare in head injury, but this complication is important as it is a potentially treatable cause delayed onset of intracranial hemorrhage. Authors report one case of traumatic aneurysm involving A1 and A2 junction of anterior cerebral artery. MATERIALS AND METHODS: A-28-year-old man with traffic accident was examined with brain CT & cerebral angiography. RESULTS: l) Brain CT:lnitial scan shows multiple skull fractures involving right frontal bones with subarachnoid hemorrhage and pneumocephalus. Follow-up scan shows intracerebral hemorrhage at bilateral frontal lobes. 2) Cerebral angiography:A traumatic aneurysm which is slowly filling and delayed emptying is noted at the junctional portion of A1 and A2 segment of the anterior cerebral artery. CONCLUSION: This report demonstrates radiologic findings of traumatic aneurysm at anterior cerebral artery with the brief review of the literatures.