Two patients experienced severe brain swelling during the evacuation of acute subdural hematomas. Postoperative computed tomographic (CT) scans revealed delayed extradural hematomas on the sides opposite the subdural hematomas. Extradural bleeding occurred in the area of the fractured skull. One patient improved neurologically after evacuation of the extradural hematoma, and the other was not operated because he was moribund. Drilling exploratory burr holes in the fractured area may have been a better strategy than awaiting a postoperative CT scan. The reduction of intracranial pressure after the removal of subdural hematoma was postulated to be the most important factor contributing to the formation of the extradural hematoma.