Patients (12) have had Greenfield vena cava filter placement above the renal veins since 1975. The indication for placement was most commonly contraindication to anticoagulation or recurrent pulmonary embolism during treatment. The follow-up consisted of physical examination, isotope phlebography-lung scan, venous Doppler evaluation, serum specimen evaluation of renal function, and abdominal roentgenograms. The follow-up averaged 16.9 .+-. 6.2 mo. (range 5 wk-58 mo.) in 10 patients. Five patients died after filter insertion, but no death was attributable to filter placement or recurrent embolism. Renal function was unchanged in all patients. Recurrent embolism was documented postoperatively in 1 patient. Migration of the filter was not observed. The vena cava was demonstrated to be patent in all patients. Two patients had evidence of embolus trapped in the filter.