Background The objective of this study was to assess the clinical safety and efficacy of vena cava filter (VCF) placement,with particular emphasis on the incidence and risk factors of inferior vena cava thrombosis (VCT) after VCF placement.Methods Clinical data of patients with venous thromboembolism (VTE),with or without placement of VCF,were analyzed in a retrospective single-center audit of medical records from January 2005 to June 2009.The collected data included demographics,procedural details,filter type,indications,and complications.Results A total of 168 cases of VTE (82 with VCF; 86 without VCF) were examined.Over a median follow-up of 24.2months,VCT occurred in 18 of 82 patients with VCFs (11 males,7 females,mean age 55.4 years).In 86 patients without VCFs,VCT occurred in only 6 individuals (4 males,2 females) during the study period.VCT was observed more frequently in patients fitted with VCFs than in those without VCFs (22% vs.7.0%).Conclusions The incidence of VCT in patients with VTE after VCF implantation was 22% approximately.Anticoagulation therapy should be continued for all patients with VCF placement,unless there is a specific contraindication.Almost all instances of VCT in patients with VCF implants in our study occurred after stopping anticoagulation treetment.The use of VCFs is increasing,and more trials are needed to confirm their benefit and accurately assess their safety.