PURPOSE: To describe clinical experiences of the use of Bird's Nest inferior vena cava(IVC) filter. MATERIALS AND METHODS: Between August 1991 and August 1997, IVC filter was percutaneously inserted in 51 patientswith pulmonary embolism(PE) and deep vein thrombosis of the lower extremities. Indications for the placement ofthis filter were contraindication to anticoagulation in 17 patients, prophylaxis of PE in 17, failedanticoagulation in 11, massive PE with residual floating thrombus in three and complications involvinganticoagulation in 3. In order to delineate the location of renal vein and extension of deep vein thrombosis intothe IVC, all patients under went inferior vena cavography before filter placement. Thirty filters were insertedthrough the right femoral vein, 19 through the right internal jugular vein and three through the left femoralvein. The patients involved were followed up for periods ranging from one week to six years (mean, 10 months). RESULTS: A Bird's Nest IVC filter was placed in the infrarenal IVC in 44 patients and in the suprarenal IVC in7. Certain complicatioins ensued. IVC penetration occurred in three patients(5.9%), and in seven(1.37%) the filterwire prolapsed. Except for transient pain, however, there were no serious IVC penetration-related complicationsand no evidence of recurrence of PE in the cases involving prolapse of the filter wire. During follow up,clinically suspected recurrent PE was noted in two patients(3.9%), but there was no evidence of newly developedocclusion of the IVC. CONCLUSION: In patients who under went follow up, Bird's Nest IVC filter effectivelyprevented the development and recurrence of PE, and there were no complications. To prevent of penetration of theIVC and prolapse of the filter, however, technical skill was needed.