Data regarding inferior vena cava (IVC) filter use and complications are scarce. This study evaluates the safety and efficacy of IVC filters over a 4-year period at two adult tertiary care hospital sites. A retrospective observational study was conducted of consecutive admitted patients who underwent insertion of an IVC filter between 1 January 2007 and 31 December 2010. The main objective of the study was to evaluate the safety and efficacy of IVC filters. We identified 338 patients with an attempted filter insertion who were followed for a median 16.3 months. Ninety-one percent of filters inserted were for an appropriate indication. Sixty-eight patients (20% of all patients) had one or more filter-related complication. Despite a median time after filter insertion to start anticoagulation of 2 days (interquartile range 3 days) for prophylactic and 6 days (interquartile range 7 days) for full dose, 38 patients (11% of all patients) had one or more thrombotic complications during follow-up. In a subgroup of patients with complete anticoagulation information available, thrombotic complications occurred in 18, 16, and 8% of patients receiving no, prophylactic, or full dose anticoagulation after IVC filter insertion, respectively (NS; P = 0.13). IVC filter use in our study was associated with a substantial rate of complications including thrombotic complications. This study highlights the need for further research regarding the safety and efficacy of IVC filters and the role for early initiation of anticoagulation.