The Randomized Evaluation of Long-Term Anticoagulation Therapy (RE-LY) trial compared the efficacy and safety of dabigatran (Pradax in Canada and Pradaxa in Europe), a new oral direct thrombin inhibitor that does not require blood test monitoring, to warfarin in 18,113 patients with atrial fibrillation and additional stroke risk factors. Patients were randomized to dabigatran 110 mg or 150 mg twice daily vs. warfarin and followed for median 2 years.  In comparison to warfarin, the higher dose of dabigatran was associated with greater efficacy and similar bleeding risk and the lower dose was associated with similar efficacy and lower bleeding risk (level 1 [likely reliable] evidence). Dabigatran 150 mg reduced the composite primary outcome of stroke or systemic embolism (2.2% vs. 3.3%, p < 0.001, NNT 91), and vascular mortality (4.5% vs. 5.3%, p = 0.04, NNT 125), with no significant difference in the risk of major bleeding (5.3% vs. 6.2%). The lower dose of dabigatran reduced risk of major bleeding (5.4% vs. 6.2%, p = 0.003, NNT 125) and had a similar rate of stroke or systemic embolism (3% vs. 3.3%) (N Engl J Med 2009 Sep 17;361(12):1139). Dabigatran is currently in phase III trials in the United States.