An intravascular catheter system for properly implanting a stent in a body lumen generally comprising a catheter having an elongated shaft with an inflatable balloon formed of compliant material and a stent mounted on the working length of the balloon. The balloon material is compliant within the working range of the balloon to provide substantial radial expansion. The wingless radially expansive balloon expands in a uniform manner, thereby producing uniform expansion and implantation of the stent. Another embodiment is directed to a balloon catheter having a semi-compliant balloon formed at least in part of a block copolymer. Axial elongation during inflation may be prevented by axial stretching or orientation during balloon production process or by mechanical device fitted on the catheter.
