The Value of irradiation in the treatment of gliomas and other brain tumors has been well established. In most patients, however, this therapy achieves only palliation, and a permanent cure is produced in but a small minority of cases. Most patients, therefore, present with residual or recurrent symptoms following the initial course of radiotherapy. The physician who is contemplating a repeated course must consider that recurrent symptoms may be due to delayed radiation changes in the brain instead of regrowth of tumor. In tumor reappearance, further radiotherapy may be of value, whereas it is contraindicated if the symptoms are due to previous radiation. If there are signs of increased intracranial pressure, then regrowth of tumor is almost certain. Radioisotope brain scanning, pneumoencephalography, or cerebral angiography can be performed to find evidence of tumor regrowth. In most cases with recurrent symptoms following radiation therapy for brain tumor, the determination of previous doses of radiatio...