Venous thromboembolism is a common condition affecting 7.1 persons per 10,000 person-years among community residents. Incidence rates for venous thromboembolism are higher in men and African Americans and increase substantially with age. It is critical to treat deep venous thrombosis at an early stage to avoid development of further complications, such as pulmonary embolism or recurrent deep venous thrombosis. The target audience for this guideline is all clinicians caring for patients who have been given a diagnosis of deep venous thrombosis or pulmonary embolism. The target patient population is patients receiving a diagnosis of pulmonary embolism or lower-extremity deep venous thrombosis.