The present invention relates to a balloon catheter system for draining and/or supplying fluid from/into hollow organs, body cavities or cysts, comprising a conduit catheter with an open distal end, a hollow needle guided in a separate guide conduit and a balloon surrounding the catheter stem at the distal end of the conduit catheter. The conduit catheter with the hollow needle can be inserted from outside into the hollow organ via a guide catheter, into the body cavity or cyst, the balloon can be filled with filling medium via the hollow needle through an opening formed in the guided duct and provided in the lumen of the balloon, and it can be fixed in the hollow organ, body cavity or cyst. The hollow needle can be removed from the guide duct after filling the balloon. The balloon and the conduit catheter remain in the hollow organ, body cavity or cyst.
