Warfarin, a vitamin K antagonist, is currently the most extensively used oral anticoagulant world-wide. It is prescribed for a variety of indications and has undergone extensive clinical study. Still, despite wide usage and considerable accumulated data from clinical trials demonstrating efficacy for a variety of thrombotic and thromboembolic conditions, warfarin is underutilized because its management is complex for both patients and physicians. However, despite these limitations, warfarin can be managed with relative safety, even in an elderly population.