Most patients who present with deep vein thrombosis (DVT) can be treated with weight-adjusted, fixed-dose, low molecular heparin as an outpatient. The subsequent duration of oral anticoagulant therapy should be individualized according to the risk of recurrent venous thromboembolism and the risk of anticoagulant-induced bleeding. The risk of recurrence is low if thrombosis was provoked by a major reversible risk factor such as surgery; 3 months of treatment is usually adequate for such patients. The risk of recurrence is high if thrombosis was unprovoked ("idiopathic") or associated with a nonreversible risk factor such as active cancer; at least 6 months, and sometimes indefinite, anticoagulant therapy is indicated for such patients. The presence of an antiphospholipid antibody, and other selected thrombophilic states, favors more prolonged therapy within each of the categories noted previously. Systemic thrombolytic therapy helps to restore venous patency and probably reduces the risk of the postthrombotic syndrome; however, it is associated with an unacceptable risk of bleeding. Catheter-directed thromboylsis, particularly for isolated iliofemoral thrombosis, may be beneficial and needs further evaluation in controlled trials.