The use of oral anticoagulation (OAC) in the elderly population with atrial fibrillation (AF) treated in long-term care (LTC) facilities is inconsistent. We examined the magnitude and sources of the gap between indicated and prescribed OAC in the elderly population with AF. We retrospectively scanned the electronic medical record (EMR) and pharmacy data of 25 LTC facilities in Ontario, Canada. The diagnosis of AF was drawn from EMR. Different attributable risk factors for possible failure to prescribe OAC were examined. In total, 3378 active resident data were examined in the 25 LTC facilities. All the residents were ae65 years old with mean age of 85 +/- 8 years and 2449 (72%) were female. We identified 433 (13%) residents with AF with mean age 87 +/- 7 years and mean CHADS2 score of 3 +/- 1. Out of all residents with AF, 273 (63%) were on OAC therapy. Residents were mostly treated with warfarin (N = 114 (42%)), rivaroxaban (N = 71 (26%)) or apixaban (N = 62 (23%)) followed by dabigatran (N = 26 (10%)). Antiplatelet drugs as the only stroke prevention therapy were used in 88 (20%) residents, and 28 (6%) residents were on anticoagulation and antiplatelet drugs. Seventy-two (17%) residents were not on any antiplatelet or antithrombotic therapy. None of the potential attributable risks identified consistently correlated with the failure to prescribe indicated therapy. This data set suggests that 37% of eligible elderly LTC residents failed to receive recommended stroke prevention therapies.