Anticoagulant therapy is the standard treatment of venous thrombo-embolism (VTE). Permanent inferior vena cava (IVC) filter is an important adjunctive therapy in these patients to prevent the complications like potentially fatal pulmonary embolism and chronic thrombo-embolic pulmonary hypertension. We studied patients with proximal deep vein thrombosis (DVT) of lower limbs and recurrent pulmonary thrombo-embolism (PTE), who were put on permanent IVC filters for the prevention of further episodes of PTE. The efficacy of filters in prevention of PTE was assessed by clinical history and was supported by follow-up (99m)Tc-MAA lung perfusion scintigraphy. We prospectively enrolled 7 patients of PTE, who were put on IVC filter from July 2002-April 2005. All patients had (99m)Tc-MAA lung perfusion scan before filter implantation. Percutaneous IVC filter placement in infra-renal position was done. All patients were put on adequate oral anticoagulant treatment with target INR of 2.0-3.0. At follow-up two patients died - one died of intractable right heart failure at 6 months and other died of carcinoma colon metastasis after 16 months. The mean follow-up of rest of five patients was 3.5 years (range 20-54 months), and none of them had clinically evident further episode of DVT or PTE. Their repeat lung perfusion scan at 1 year of follow-up showed marked improvement in perfusion with no evidence of additional fresh/new defects. Follow-up (99m)Tc-MAA lung perfusion scan in PTE patients, who are on IVC filter, can demonstrate the significant improvement in lung perfusion secondary to prevention of further pulmonary embolism episodes and resolution of pulmonary thrombus by continued anticoagulant therapy.