OBJECTIVES: To compare mortality, healthcare utilization and cost burden of patients who suffered major bleeding during the 180 days after diagnosis of non-valvular atrial fibrillation (NVAF) with patients who did not. METHODS: Based on the 2005-2007 U.S. Medicare advantage insurance claim files, patients aged 65 years and older who have had two or more primary diagnoses for NVAF occurring within 30 days of one another were selected. The 180-day follow-up mortality, healthcare facility use and costs for patients with and without major bleeding were compared. Risk adjustment was performed using the propensity score matching method with the ProbChoice™ algorithm. RESULTS: Out of the patients who were identified with NVAF (n=18,575), 266 (1.43%) suffered a major bleeding during the 180 days after NVAF diagnosis. Patients were not significantly different in terms of gender, region, and baseline comorbid conditions. After risk-adjustment for pre-specified covariates, mortality (9.77% vs. 0.38% p<0.0001), outpatient emergency room (ER) visits (84.21% vs. 43.23% p<0.0001), ischemic stroke (44 vs. 8/100 person years), myocardial infarction (10 vs. 2/100 person years) and osteoporotic fracture (7 vs. 1/100 person years) were all higher for patients who suffered a major bleeding compared to those who did not.  Besides inpatient costs ($26,568 vs. $8,929), risk-adjusted outpatient ER costs ($1,280 vs. $744) were also higher for major bleeding patients. The overall risk-adjusted difference in healthcare costs is significant ($35,691 vs. $10,480 p<0.0001). CONCLUSIONS: Most of the adverse events analyzed were higher for patients who suffered a major bleeding after NVAF relative to patients who did not. Total healthcare utilization and costs were also significantly increased.