This invention provides prosthesis delivery systems with atraumatic tips that can be dislodged from the catheter so that the catheter can be easily removed from the body after expanding the prosthesis, by pulling the catheter proximally. With the tip dislodged, the catheter, which is of smaller diameter than the tip can be removed even in instances where the prosthesis does not expand the lumen to a large diameter. This invention also provides prosthesis delivery systems with a contoured protective outer sheath having smaller diameters in proximal portions that normally are acutely bent when the system is in the body, than in distal portions corresponding to the position of the prostheses. These systems are more flexible and the sheaths less likely to kink, especially when configured as part of a large delivery system.