Abstract: A removable intravascular filter system traps emboli and other solid materials in connection with intravascular medical procedures such as the placement of a stent or a catheter balloon. The system involves a hollow guidewire and an actuating wire movable within the guidewire to actuate the filter membrane. Embodiments of the filter system include biased closed and biased open filter configurations, and are easily routed through a patient's artery and deployed. Optionally, the actuating wire can be removed and a substitute wire can be inserted into the hollow guidewire. Control mechanisms can help the operator limit movement of the actuating wire during deployment and/or collapse of the filter membrane. Preferred filter membranes are configured to maximize both blood flow and emboli capture.