Thirty patients with Stage III/IV cancer and thromboembolic complications between 1987-89 were reviewed. Twelve patients had a deep venous thrombosis proximal to the calf diagnosed by duplex scanning or contrast venography, 15 patients had a pulmonary embolism diagnosed by a high-probability pulmonary ventilation/perfusion scan or arteriogram, and three patients had both deep vein thrombosis and pulmonary embolism. Patients were treated primarily with anticoagulation (Group A = 20 patients) or a Greenfield filter (Group B = 10 patients). Seventy-five percent (15/20) of the Group A patients developed 19 bleeding or thrombosis-related complications: major bleeding (7), recurrent deep venous thrombosis/pulmonary embolism (4), inability to attain consistent therapeutic anticoagulation levels (3), heparin-induced thrombocytopenia (3), or progression of deep vein thrombosis (2). A Greenfield filter was eventually placed in 10 (50%) of the Group A patients without complications. Thirty percent (3/10) of the Group B patients developed progression of deep vein thrombosis that required anticoagulation. One other Group B patient died due to a guidewire-induced arrhythmia. Although patients with advanced cancers and venous thromboembolic disease have a high complication rate with either treatment, initial treatment with a Greenfield filter appears more definitive. Anticoagulation should be reserved for patients with progressive, symptomatic deep vein thromboses after placement of a filter.