A catheter guidewire for facilitating introduction of a flexible catheter into the human body (e.g., into the bladder) has a proximal end having a first stiffness which is sufficient to facilitate guidance of a stiff plastic expansion sheath through the tissue. A distal end of the guide wire has a second stiffness, substantially less than the first stiffness, to avoid damage to internal walls of the bladder. Preferably, the guide wire incorporates an intermediate portion having a stiffness between the first stiffness value and the second stiffness value.
