Acute extradural hematoma, a collection of blood between the inner table of the skull and the dura, generally occurs in coup craniocerebral trauma with skull fracture. We report here a case of a 52-year-old female who had had a traffic accident. She suffered a serious wound consisting of a subcutaneous hematoma with skull fracture and so called Battle's sign on the left occipital region but not wounded in any other region. CT scan obtained shortly after the injury demonstrated a thin acute extradural hematoma with intracranial air under the subcutaneous hematoma in the left occipital region, and another hematoma with subarachnoid hemorrhage due to contrecoup head trauma in the right frontal region. We treated her conservatively with a common drip. She sometimes vomited during the several hours after admission. CT scan six hours later showed that the contrecoup extradural hematoma had enlarged. Immediately, we carried out the evacuation of the hematoma with decompressive craniectomy. Her scalp, cranium and frontal skull base over the extradural hematoma were without injury, and multiple small haemorrhages were found to have occurred on the surface of the dura that had been separated from the inner table of the skull. After the operation, the patient recovered consciousness. Contrecoup acute extradural hematoma is very rare. It seems that the appearance of hematoma in our case resulted from the frontal dural separation due to distortion of the cranium brought on by the force of the impact and the subsequent gradual growth of the hematoma under the stimulation of several bouts of vomiting.