Device for determining the relative position of two or more catheters in the human body, there being disposed on each catheter (4, 5), preferably in the area of the catheter tip, at least one measuring electrode (ME1-ME8; ME9, ME10) which can be connected to a voltage source together with one or more measuring electrodes of a further catheter, wherein the resistance between the measuring electrodes, and hence the distance of the measuring electrodes, can be determined via a current measurement.