Deep vein thrombosis (DVT) and pulmonary embolism (PE) are both characterized by unreliable clinical diagnosis and significant long-term sequelae. In patients with DVT, popliteal valvular insufficiency is associated with increased risk for postphlebitic syndrome. Current data show thrombolytic therapy to be more effective than anticoagulation for DVT, accomplishing significant or complete clearing of the deep venous system in nearly half of all patients treated. Results of investigation show lytic therapy to also be more effective than heparin in treatment of PE, both in terms of acute resolution and long-term function.