Randomized trials have supported a role for radiation therapy in the initial management of Glioblastoma Multiforme (GBM) for over twenty-five years. Although technological advances in imaging and three-dimensional treatment planning have reduced the toxicity for patients and have allowed safe radiation dose escalation, unfortunately they have not produced a correspondingly dramatic improvement in overall survival. The dose of 60 Gy partial brain RT remains the standard of care for patients with newly diagnosed GBM. Recently completed randomized trials of brachytherapy and radiosurgery do not support these modalities in the initial management of GBM, but these and other focal RT techniques such as intensity modulated radiation therapy enable safe retreatment in selected patients. Future studies will need to explore radiation biologic response modification and radiosensitization through targeted therapies.