This is a brief review of some of the more important aspects of pharmacology and clinical management of anticoagulant therapy for venous thromboembolism. Some controversial aspects of treatment with respect to drug dosage, laboratory monitoring, and intensity and duration of therapy have been discussed. Thromboembolic complications can be reduced by extending the duration of anticoagulant therapy to a minimum period of 4 months after hospital discharge. Longer periods of treatment may be necessary in patients with recurrent deep venous thrombosis or pulmonary embolism. Hemorrhagic complications can be minimized by proper attention to laboratory monitoring and awareness of drug interactions and side effects.