In the past at our institution, insertion of the vena cava filter was recommended almost exclusively for recurrent pulmonary emboli in anticoagulated patients or in those with emboli and contraindications to anticoagulation. More recently, prophylaxis has become a frequent indication for patients with extensive deep vein thrombosis and contraindications to anticoagulation. Herein, we review a recent series of caval filter insertions to determine if increased utilization of this technique is justified in terms of morbidity and effectiveness. Twenty-one filters were inserted in 20 patients during a 1-year period. The operative mortality rate was 0 and satisfactory filter placement was achieved in 90 percent of patients. There were no documented instances of recurrent emboli or vena cava thrombosis. These data suggest that use of the filter is justified as prophylaxis for patients at high risk for an initial pulmonary embolus in a clinical setting where heparin therapy is not appropriate.