BACKGROUND Oral anticoagulants have seen large popularity due to their ease of administration and proven benefit in a variety of conditions. In an examination of patients in Manitoba, 7.2% of the elderly population was being treated with warfarin therapy, a proportion which is likely similar across Canada. For atrial fibrillation, the dose of warfarin is titrated using INR as a guide to a target of 2.0-3.0, a therapeutic range with significant evidence of decreased thromboembolic events while minimizing the risk of major hemorrhage2. Other indications for anticoagulation therapy include presence of a mechanical heart valves, a history of deep vein thromboses or pulmonary embolism(s), or other pro-thrombotic conditions.