Abstract: The balloon dilatation catheter has a first lumen extending along the entire length of a shaft, which lumen is connected to a pump and, at the distal end of the catheter, to the inside of the balloon. Through this lumen there also passes a support wire connected firmly to the catheter. The shaft has an additional lumen which opens outwards via an opening behind the proximal end of the balloon. A controllable guide wire can be introduced into this lumen via an attachment piece. Similarly, a measuring apparatus or an apparatus for introducing a contrast medium or drug can be connected to this additional lumen. The catheter is particularly suitable for treating strictures in an arterial ramification.