A fixed wire balloon catheter for use in angioplasty includes an elongated flexible thin walled metal tube which carries an inflatable balloon at its distal end. A metal core member of smaller outer diameter than the metal tube is attached to the distal end of the tube to provide support for and guiding of the balloon section. The proximal end of the balloon is connected either to the distal end of the metal tube or to an intermediate waist tube, with the core extending distally from the metal tube through the balloon. The distal end of the balloon is secured to the core. A vent arrangement is provided to purge the catheter of gases prior to use.