A device for tracking catheters includes an oscillator which is coupled to a transmit coil. The transmit coil is rotated in a direction transverse to the longitudinal axis of the transmit coil. A receive coil situated on the guide wire of a catheter inserted into a patient's body receives the signal transmitted from the transmit coil. A rectifier rectifies the received signal, and a filter filters the rectified received signal. A strobe circuit provides strobes of light in response to the rectifie received signal and cooperates with bar image forming circuitry and structure to provide an image of a bar which is aligned with the longitudinal axis of the receive coil, which is indicative of the orientation of the catheter and guide wire on which the receive coil is situated. A bar display indicates the relative proximity of the transmit coil to the receive coil, and a numeric display provides a read-out of the distance between the transmit coil and the receive coil.