Abstract. During endovascular interventions, the radiologist relies on 2D projection images to advance the guide wire, while often a preoperative 3D image of the vasculature is available. To take full advantage of the 3D information, two different methods are proposed and compared for 3D guide wire reconstruction and visualization in the 3D vasculature. Upon tracking the guide wire in biplane fluoroscopy images, the first approach utilizes a precalibrated C-arm system to determine the guide wire position in the 3D coordinate system of the vasculature. In the second method the relation between the projection images and the 3D vascular data is determined using intensity based 2D-3D registration. Based on a study on an anthropomorphic phantom, it is shown that the calibration method is highly accurate, but that in case of imperfect geometry knowledge results rapidly degrade. For 2D-3D registration, similar accurate results were obtained with a 97.8 (84.2)% success rate if the registration starting position was within 4 (8) degrees rotation and 5 (10) mm translation of the reference position. The latter method has also been used to succesfully reconstruct a guide wire in a patient dataset.