OBJECTIVES: There is limited information associating CHA2DS2VASc and ATRIA scores among patients newly prescribed an anticoagulant and stroke/systemic embolism (SysEmb) and bleeding event rates in the real-world. METHODS: A retrospective analysis of a de-identified, pharmacy-medical claims database was conducted in patients with atrial fibrillation (AFIB) and new to dabigatran or warfarin (no drug 6-months prior) from 1/1/10-2/28/11. Patients had continuous eligibility of 12 months prior to and 4 months post initial anticoagulation claim date. Patients’ CHA2DS2VASc, and ATRIA risk scores were determined using demographic data and ICD-9/CPT codes (≥2 separate dates) in the prior 12 months. Stroke/SysEmb risk was classified by CHA2DS2VASc score as: low-risk=0-1, moderate-risk=2, and high-risk ≥2.  Bleeding risk using ATRIA score was classified as: low-risk=0-3, moderate-risk=4, and high-risk ≥5.  Stroke/SysEmb and bleeding events rates/100 patient years were based on ICD-9 codes in the 4 months post anticoagulant initiation.  RESULTS: A total of 8,162 patients (warfarin=7,072 and dabigatran=1,090) were analyzed: age=75±11 years (82% ≥65 years); 57% were male; with a CHA2DS2VASc and ATRIA risk scores of 3.8±1.7 and 2.8±1.9, respectively. At 4 months, Stroke/SysEmb and overall bleeding event rates were 5.9% (95%CI 5.4% - 6.4%) and 11.1% (95%CI 10.4% - 11.8%) respectively. As CHA2DS2VASc or ATRIA scores increased, so did the rates for Stroke/SysEmb or bleeding events: Stroke/SysEmb low-risk: 0.88% (95%CI 0.18% - 1.58%), moderate-risk: 1.76% (95%CI 0.95% - 2.57%) and high-risk: 7.05% (95%CI 6.43% - 7.67%); bleeding by ATRIA, low-risk: 8.62% (95%CI 7.93% - 9.31%), moderate-risk: 16.79% (95%CI 14.15% - 19.43%) and high-risk: 21.69% (95%CI 19.21% - 24.17%).  CONCLUSIONS: Increasing CHA2DS2VASc and ATRIA scores were associated with greater rates of Stroke/SysEmb or bleeding events in this real-world, anticoagulant-treated population. Using claims-based CHA2DS2VASc and ATRIA scoring as a screening tool may identify patients at risk of thromboembolic and bleeding events when initiating anticoagulation therapy.