OBJECTIVES: We evaluated the generalizability of Medicare fee-for-service data for patients hospitalized with injuries. METHODS: We used 1998-2000 Medicare hospitalization data and National Hospital Discharge Survey (NHDS) data to analyze patients aged 65 years and older with principal injury diagnoses. RESULTS: Demographics and injury patterns were similar in Medicare data and NHDS Medicare data. Injured patients without Medicare or health maintenance organization coverage were younger, less likely to have hip fractures, and more likely to have head or chest injuries. Mortality and discharge to long-term care were not significantly affected by insurance coverage, after we controlled for injury type and severity, age, gender, and comorbidity. Medicare patients had slightly longer hospital lengths of stay. CONCLUSIONS: Hospital outcomes are generally similar among older patients with a given anatomic injury, regardless of insurance coverage.