Abstract only 463 Background: Hepatocellular carcinoma (HCC) is an increasingly common and highly morbid malignancy worldwide, including the US. For early stage patients ablative strategies are important potentially curative treatment options. Stereotactic body radiotherapy (SBRT) has emerged as a promising non-surgical ablative therapy, although it is technically demanding and its comparison with radiofrequency ablation (RFA) remains confined to a single institution retrospective review. We queried the Surveillance, Epidemiology, and End Results (SEER)-Medicare linked database to assess RFA and SBRT use in the US. Methods: We identified patients greater than 65 years old who were diagnosed from 2004-11 with stage I or II HCC and treated with RFA or SBRT. Survival analysis was conducted using Kaplan-Meier curves and log rank test. Factors associated with overall survival (OS) and early ( ≤ 90 day) hospital admission post-treatment were identified using propensity score (PS) adjusted multivariate analysis. Results: 825 patients were identified, 747 treated with RFA and 78 SBRT. 22 pts received both treatments and were excluded from this analysis. The mean Charlson comorbidity index was 1.0±1.1. Median age was 74, range 66-90. Patients who received RFA were more likely to live in the West and have liver decompensation. Patients who received SBRT were more likely to be white and treated in the Midwest. After using PS matching there were 78 in each cohort. In these patients, mean overall survival (OS) was 2.25 and 2.04 yrs for RFA and SBRT, p = 0.06. Younger age, lack of liver decompensation, treatment in the West, and liver transplantation were associated with longer OS, HR 0.96, p = 0.05; HR 0.37, p = 0.002; HR 0.57, p = 0.04; HR 0.18, p = 0.008, respectively. 90 day hospitalization rates did not differ between treatments; only liver decompensation was predictive of hospitalization, OR 3.33, p = 0.032. Conclusions: In a national cohort of early stage HCC patients, treatment with RFA vs SBRT resulted in no significant difference in OS. SBRT appears to be a comparable ablative strategy to RFA in this population. This highlights the need for a randomized trial comparing these two modalities.