Gliomatosis cerebri is defined as a remarkably diffuse glioma, characterized by widespread infiltration of the central nervous system. Clinicopathologic characteristics and imaging findings have been published but valid classification remains controversial. Few reports exist regarding therapeutic options in gliomatosis cerebri. Here we review data on 17 patients treated with radiation therapy extracted from the literature, in which we focus our attention on available details of irradiation and clinical outcome and present the results of three additional patients treated at our two institutions. Radiologic-pathologic correlation in gliomatosis cerebri indicates that tumor delineation should be based on T2-weighted MRI. Radiation therapy in gliomatosis cerebri is associated with a temporary improvement in or stabilization of clinical symptoms in the majority of cases. Duration of improvement was > or = 6 months in 50% of treated patients. Survival from onset of symptoms was 23.8 months (range 8-42). Considerable variation in the natural course of the disease precludes conclusions regarding the impact of radiation therapy on survival.