A new, percutaneous vena cava filter was developed and tested in 11 dogs. Nitinol wire (0.045 cm diam) spirals were straightened and passed through an 8 French Teflon catheter into the inferior vena cava. The filter resumed its original spiral shape on warming to body temperature and was left in place up to 6 weeks. Long-term patency and capture of injected radiopaque clots were demonstrated. This new filter design may be a simple alternative to currently used implants.