Warfarin Guide offers three resources essential for systematic and careful evidence-based anticoagulation with Warfarin. First it reviews recommendations on indications, INR targets, and treatment duration from the American College of Chest Physicians 8th Edition guidelines on Antithrombotic and Thrombolytic Therapy from 2008, updated for the 2012 guideline. Second it offers a protocol for Warfarin dose adjustment depending upon INR result. And third is a discussion of protocols for the initiation of Warfarin. These resources come from point of care guides on these topics in the family medicine literature as well as the 2012 ACCP guideline. The app also offers guidance for management of peri-operative Warfarin by directing the user to oexcellent comprehensive resources for managing all anticoagulants and antiplatelet agents around surgery. The app addresses such common questions as: •which artificial heart valves require that higher level of anticoagulation? •how do I respond to an INR of 7.4? •this pt needs Warfarin, how do I get it started? •I'm adjusting the total weekly warfarin dose down by 5%, when should I recheck the INR? •when do I give Vitamin K to reverse Warfarin anticoagulation and at what dose?? This app is written and intended for practicing clinicians involved in Warfarin anticoagulation such as internists, cardiologists, family physicians, nurses, pharmacists, PA's and NP's; for resident physician trainees; and for medical students. As an educator and clinician, I am interested in feedback and I would be grateful for guidance on improving the tool.