Cases of brain necrosis following the radiation therapy of brain tumor have been reported, and in the most cases postirradiating brain damage are usually interpreted as a recurrence of the tumor. The Authors report here a case of postirradiation brain necrosis in the left frontal astrocytoma 4 years after operation. Patient's manifestations are headache, vomiting, right sided hemiparesis and focal seizures which after developing generalized seizures in association with signs of increased intracranial pressure. CT scan showed a large cystic mass in the left frontal lobe which was verified to be necrosis on operation.