Background: No randomized trials among elderly GBM patients using HRT have compared efficacy to the Stupp regimen of SRT+T, and many elderly patients in the United States receive SRT+T. Methods: We evaluated 88 consecutive patients ≥ 65 years old with GBM diagnosed from 1994-2010 who received HRT or SRT with or without concurrent T. Overall survival (OS) was calculated by the Kaplan-Meier method. Prognostic factors were evaluated using the Cox proportional hazards model and Fisher exact test. HRT consisted of 40 Gy/15 fractions, and SRT consisted of 59.4-60 Gy/30-33 fractions. Results: Patients received SRT+T (n = 26), SRT (n = 35), HRT+T (n = 21), or HRT (n = 6). Median age was 70 among SRT±T patients and 80 among HRT±T patients (P < 0.001), KPS was lower among HRT±T patients (P < 0.001), and SRT-alone patients were more likely to be treated prior to the year 2000 (P < 0.001); there were no significant differences between groups with regard to gender, tumor size or multifocality, extent of resection, or MGMT methylation status. With a median follow up of 9.7 mo, median OS was 10.1 mo (SRT+T), 9.5 mo (SRT), 10.8 mo (HRT+T), and 3.0 mo (HRT). On multivariate analysis, compared to SRT+T, mortality was significantly lower for HRT+T (AHR = 0.39; 95% CI, 0.16-0.91; P = 0.030) and higher for HRT (AHR = 3.94; 95% CI, 1.16-13.42; P = 0.028). Increasing age (AHR = 1.08; 95% CI, 1.01-1.15; P = 0.018), lower KPS (AHR = 1.03; 95% CI, 1.01-1.04, P = 0.002), and multifocal tumors (AHR = 3.18; 95% CI, 1.57-6.46; P= 0.001) were also associated with higher mortality. Conclusions: Among elderly GBM patients, HRT+T was associated with improved survival compared to SRT+T, despite older age and lower KPS at baseline. These data suggest that with the addition of T, the number of radiotherapy treatments may be reduced by half with no decrement in survival, and should be explored in a randomized setting.