BACKGROUND The addition of temozolomide (TMZ) to radiotherapy (RT) improves survival of patients with glioblastoma (GB) when compared to postoperative RT alone in patients up to 65 years of age. In older patients, RT alone has remained the standard of care because there is concern that radiochemotherapy causes excess toxicity and is less efficacious in this population, but no randomized trials have been reported. We retrospectively assessed feasibility, toxicity and outcome in elderly patients treated at a single institution with RT and concomitant TMZ. METHODS Between 04/1999 and 9/2009, 51 patients ≥65 years (median age 70 years, range 65-84) with GB were treated by RT (total dose 60 Gy in 30 fractions) and concomitant TMZ (75 mg/m(2)/day throughout RT). Biopsy only had been performed in 23 patients (45.1%), 15 patients (29.4%) had undergone partial resection, and 13 patients (25.5%) macroscopically complete resection. Adjuvant TMZ was applied in 10 of 51 patients. RESULTS Median overall survival (OS) and progression-free survival (PFS) were 11.5 (95% CI, 6.7-16.3) and 5.5 months (95% CI, 3.7-7.3 months), respectively, in the total cohort. After complete resection, partial resection and biopsy, median OS was 27.4, 15.5 and 7.9 months (p=0.002), respectively. In multivariate Cox proportional hazards regression models extent of resection (p<0.0001) and Karnofsky's performance score (p=0.002) were significant independent prognostic factors for OS. RT with concomitant TMZ was well tolerated in the majority of patients and could be completed as scheduled in 30 patients (59%). Five patients (10%) discontinued RT because of disease progression (n=4) or toxicity (pneumonia, n=1). Another 16 patients interrupted concomitant chemotherapy (cytopenia: 9; pneumonia: 2; transaminase elevation: 2; rash: 3). CONCLUSIONS RT with concomitant TMZ is a feasible regimen with acceptable toxicity in elderly patients. The promising outcome in patients with good performance status and patients with gross total resections are notable.