For almost half a century, physicians have treated noncritical patients who have acute venous thromboembolism with adjusted doses of unfractionated heparin or, more recently, fixed doses of low-molecular-weight heparin (LMWH), followed by oral warfarin for variable periods. Although both forms of heparin are safe and effective therapies to prevent recurrent venous thromboembolism (1), physicians are increasingly using LMWHs because of their longer half-life, more predictable pharmacologic effects, and convenience. The subcutaneous administration of fixed doses, adjusted only to body weight, is straightforward even outside the hospital. Despite convincing evidence that LMWH is a safe and effective treatment of venous thromboembolism on an at-home basis (2 - 3), this strategy is far from being routine practice for 2 main reasons. First, physicians fear the consequences of undertreating venous thromboembolism because pulmonary embolism can be fatal. This is particularly true for patients with primary pulmonary embolism. Indeed, LMWHs have not been as extensively investigated in patients with primary symptomatic pulmonary embolism as in patients with deep venous thrombosis (DVT). Second, physicians are concerned about convenience for the patient because of the need for careful laboratory monitoring of anticoagulation status during the first days of treatment, indispensable to guarantee the correct overlap between heparins and oral anticoagulants.