Venous thromboembolism, comprising deep vein thrombosis and pulmonary embolism, is a common disorder with at least 250 000 new events occurring each year in the United States alone. Treatment of venous thromboembolism includes anticoagulation, which is achieved initially with the use of a parenterally administered agent followed by a more prolonged course of treatment with an oral vitamin K antagonist. The duration of treatment depends on the clinical assessment of the benefit-to-risk ratio of prolonged anticoagulation versus the risk of recurrent events. In this review, we discuss some of the issues that we believe are among the most critical unanswered questions in the management of venous thromboembolism in the present era.