Chronic subdural hematoma is a very rarely observed complication after endoscopic third ventriculostomy (ETV). A 21-year-old male patient was admitted to our clinic with complaining of headache, weakness and tremor. The fundoscopic examination revealed slightly indistinct border of the papilla and neurological examination findings were normal. The cranial computed tomographic (CT) and magnetic resonance imaging (MRI) findings demonstrated three-ventricular hydrocephalus due to aqueductal stenosis and ETV was performed. The symptoms got better after the operation. At 11/2 month postoperatively the patient reapplied to our clinic with a symptom of severe headache. Cranial BT imaging demonstrated enlargement of subdural hematoma. The hematoma was treated by burr-hole evacuation and drainage and totally disappeared in the postoperative period. The follow-up CT scan was evaluated as normal. Nowadays, ETV is accepted as a safe and an alternative method for the treatment of obstructive hydrocephalus instead of shunt operation. Chronic subdural hematoma is a rarely observed complication after ETV.