Hyperperfusion syndrome (HS) is characterized by unilateral headache, seizures, and hypertension and may result in intracerebral hemorrhage. HS is a serious complication following carotid endarterectomy or angioplasty, but it is rarely reported after evacuation of chronic subdural hematoma (CSH). A 75-year-old man developed headache, seizure, and hemiparesis after evacuation of CSH. HS is diagnosed by a postoperative transcranial Doppler. His symptoms subsided with anti-hypertensive medications. Early recognition of this syndrome may be important in reducing postoperative morbidity of CSH.