As the incidence of stage I non-small cell lung cancer (NSCLC) increases among octogenarians and only selected patients are surgical candidates, an alternative treatment is necessary. This manuscript evaluates the overall survival, local tumor control rate, and treatment-related toxicity after stereotactic body radiotherapy (SBRT) in 38 octogenarians with stage I NSCLC. Treatment consisted of 45 Gy (n = 4) or 60 Gy (n = 25) in 3 fractions for patients with peripheral tumors. A risk adaptive schedule of 45-60 Gy in 3-6 fractions was used for central (n = 7) or large peripheral tumors (n = 2). An overall survival rate of 65% at 1 year and 44% at 2 years was achieved in octogenarians after SBRT. The local tumor control rate was excellent (100% at 2 years) and no grade 4 or 5 treatment-related toxicity occurred. Despite the high incidence of comorbidity in these octogenarians (Charlson score >= 5 in 16% of patients), an approach that merely provides supportive care cannot always be justified. SBRT offers octogenarians with stage I NSCLC a good treatment alternative. (C) 2009 Elsevier Ireland Ltd. All rights reserved.