Patients with cancer have an increased risk of thromboembolism. This complication is connected to a variety of different factors and is influenced by the conditions described in Virchow's triad: stasis, vascular endothelial damage, and hypercoagulability. Once thromboembolism is diagnosed, treatment in patients with cancer usually involves anticoagulation with unfractionated or low-molecular-weight heparin and progression to oral anticoagulant therapy. Duration of treatment is usually three to six months, with most patients receiving six months of anticoagulation. Patients with cancer may be at risk for recurrent thrombosis as well, despite optimal use of oral anticoagulant therapy, and some of these patients may require lifelong heparin therapy. This article describes the current treatment regimens to provide anticoagulation therapy to patients with cancer, including a discussion of the low-molecular-weight heparins and dosing parameters. Nursing interventions to help provide these treatments safely are discussed. Patients with cancer have a high rate of thromboembolism; oncology nurses should heighten their awareness of this important complication, treatment options, and appropriate nursing interventions.