OBJECTIVES: To estimate mortality, health care utility and health care cost burden of patients who suffered a stroke during the 180 days after diagnosis of non-valvular atrial fibrillation (NVAF) and compare it with patients who did not suffer a stroke. METHODS: Based on 2005-2007 U.S. Medicare advantage insurance claim files, patients aged 65 years and older who had 2 or more primary diagnoses for NVAF within 30 days of one another were selected. The 180-day follow-up event rates, health care facility use and health care cost for patients with a stroke and those without were compared. Risk adjustment was done by using the propensity score matching method with the ProbChoice™ algorithm. RESULTS: Out of patients identified with NVAF (n=18,575), 575 suffered a stroke during the 180 days after NVAF diagnosis. 94% (n=541) did not have stroke during the baseline period (180 days before NVAF diagnosis).  Patients were not significantly different in terms of gender, region, and baseline comorbid conditions. After risk-adjustment for pre-specified covariates, mortality (7.14% vs. 2.09% p<0.0001), outpatient emergency room (ER) visits (79.97% vs. 46.34% p<0.0001), acute coronary syndrome (43 vs. 16/100person years), transient ischemic attack (73 vs. 4 /100 person years), major bleeding (85 vs. 4 /100 person years) and myocardial infarction (32 vs. 9/100 person years) were all higher for patients who suffered a stroke compared to those who did not.  Besides inpatient cost ($24,116 vs. $20,828), risk-adjusted outpatient ER costs ($921 vs. $873) were also higher for stroke patients. Overall risk-adjusted difference in health care costs is significant ($33,430 vs. $16,375 p<0.0001). CONCLUSIONS: Most of the adverse events analyzed were higher for patients who suffered a stroke after NVAF relative to patients who did not. Total health care utility and health care cost were also significantly increased.