A method for performing an angioplasty procedure for treating one or more stenoses in a blood vessel and branches thereof of a patient by the use of a low profile balloon-on-a-wire catheter having a flexible elongate tubular member with proximal and distal extremities and with a balloon inflation/deflation lumen extending from the proximal extremity to the distal extremity, an inflatable balloon carried by the distal extremity of the flexible elongate tubular member, means carried by the flexible elongate tubular member for establishing communication between the lumen and the interior of the balloon and removable inflation means removably secured to the proximal extremity of the flexible elongate tubular member for supplying an inflation fluid to the lumen for inflating and deflating the balloon, the method comprising the steps of inserting the balloon-on-a-wire catheter into the vessel so that the balloon is disposed in a selected stenosis in the vessel, placing the removable inflation means on the proximal extremity of the flexible elongate tubular member so that it is in communication with the lumen, inflating the balloon to create an enlarged flow passage through the selected stenosis, removing the inflation means removably secured to the proximal extremity of the flexible elongate tubular member, introducing a balloon catheter over the flexible elongate tubular member utilizing the flexible elongate tubular member as a stand-alone guide wire for guiding the balloon of the balloon catheter into the selected stenosis while the balloon of the balloon-on-a-wire catheter is deflated, inflating the balloon of the balloon catheter to create a larger flow passage in the stenosis, deflating the balloon of the balloon catheter and removing the balloon catheter, redeploying the balloon-on-a-wire catheter so that the balloon thereon is in registration with another stenosis, placing the removable inflation means on the proximal extremity of the flexible elongate tubular member so that it is in communication with the lumen, inflating the balloon on the balloon-on-a-wire catheter to create an enlarged flow passage through the another stenosis, removing the inflation means removably secured to the proximal extremity of the flexible elongate tubular member, introducing a balloon catheter over the flexible elongate tubular member utilizing the flexible elongate tubular member as a stand-alone guide wire for guiding the balloon of the balloon catheter into the another stenosis while the balloon of the balloon-on-a-wire catheter is deflated, inflating the balloon of the balloon catheter to create a larger flow passage in the another stenosis, deflating the balloon of the balloon catheter and removing the balloon catheter and the balloon-on-a-wire catheter from the another stenosis.