Objective To investigate the protection effect of inferior vena cava filter on pulmonary embolism in patients with deep venous thrombosis(DVT) of lower extremities. Methods Inferior vena cava filters were placed in 55 patients with DVT. Simon Nitiol filter(SNF) was used in 25 cases,Trap Ease filter(TEF) in 13 cases and Antheor Temporal filter(ATF) in 17 cases.10 patients with DVT were treated by non operation therapy,45 patients by operation and transluminal angioplasties.Whether patients occurred pulmonary embolism was observed clinically,and the form and site of SNF and TEF were monitored by periodic fluoroscopy . Results Inferior vena cava filter was placed successfully in all patients.Symptoms and signs of DVT disappeared in all the patients after treatment . None of the putients occurred pulmonary embolism in this series. One case occurred inferior vena cava thrombolism in 16 months after SNF placement. Thrombus attached to ATF after the ATF taking off from inferior vena cava was found in 17 cases.Conclusions Inferior vena cava filter placement is a simple, safe and efficient method to prevent pulmonary embolism in a short period.But its long term complications should be considered and investigated.