Two cases of delayed cerebral radionecrosis with cystic presentation are reported. The patients had received radiation therapy for a cutaneous tumor 16 and 12 years before. Surgical extirpation of the cerebral lesion permitted to confirm the diagnosis and to treat the patients with success. A cystic aspect has been reported rarely in the neuroradiologic descriptions of the cerebral radionecrosis in the literature. Its mechanism is discussed. The treatment of the delayed cerebral radionecrosis is not clearly established, but a cystic presentation is an argument for surgery.