A new vena caval filter that can be inserted percutaneously through an angiographic catheter is described. The filter is secured by controlled penetration of the caval wall and is designed for percutaneous retrieval. The filter was easily and safely placed, and removed in 11 mongrel dog and, in an in vitro study, the filter was shown to be highly effective and less dependent than the Greenfield filter on positioning. The filter apparently will be suitable for prophylactic placement in patients at high risk for pulmonary thromboembolic disease.