Background: Although the standard of care for early stage NSCLC is surgery, SBRT has emerged as an alternative for elderly patients who refuse surgery or are medically inoperable. As patterns of care may evolved since the introduction of SBRT for NSCLC in 2003, we investigated the adoption of SBRT vs. surgery in the Surveillance, Epidemiology, and End Results (SEER)– Medicare database in the years 2007-2009. Methods: We identified patients age > 67 who were diagnosed with stage I NSCLC from 2007 through 2009 and had undergone SBRT or surgery based on Medicare claims. Patient and hospital referral region (HRR) characteristics were recorded. Disability status (DS), a validated claims-based proxy for poor performance status, Elixhauser comorbidity index, and life expectancy (LE) were calculated using Medicare claims 12 months prior to diagnosis. The trend in receipt of SBRT was assessed for different categories of age, DS, and LE for patients whom SBRT was available in their HRR of residence. Results: There were 383 SBRT patients and 3,852 surgery patients. The proportion of patients undergoing SBRT rose from 4.4% in 2007 to 12.7% of treated patients in 2009 (p<.001). Patients who were older (Age 85-94; Odds Ratio (OR) vs. age 66-69: 5.98 [95% CI 3.34-8.08] , p<.001), female (OR 1.49 [95% CI 1.16-1.91], p=.002), with higher comorbidity (3+ conditions vs. 1: OR 4.23 [95% CI 2.97-6.02], p<.001) or disability status (Highest DS quartile vs. lowest OR 1.96 [95% CI 1.41-2.72],p<.001) were significantly more likely to undergo SBRT. The proportion of patients receiving SBRT (vs. surgery) increased in particular for patients with a shorter LE: SBRT use among patients with LE < 5 years from 11.8% in 2007 to 35.0% in 2009. In comparison, SBRT use for LE ≥ 5 years increased from 3.9% to 10.6% in the same period. Conclusions: The use of SBRT has disseminated rapidly into the care of older persons with early localized lung cancer, particularly those shorter life expectancies. Prospective studies are needed to identify patient and treatment factors associated with optimal outcomes.