A guide wire for a catheter comprises an elongated hollow shaft has a lumen for delivering or leading away the fluid, and an insertion aid in the form of a flexible wire coil connected coaxially to a distal end of the hollow shaft. The wire coil has a guide wire tip arranged at a distal end, a core wire being arranged in the lumen of the hollow shaft to control the flexibility of the guide wire. The core wire extends out of the lumen and through the wire coil to the guide wire tip. A distal inner area of the wire coil adjacent to the guide wire tip in a proximal direction communicates with the lumen of the hollow shaft by means of a fluid channel formed next to the core wire and has at least one outwardly open passage opening for the fluid to be introduced or removed.