A balloon dilatation catheter for the dilatation of a prostatic urethra having a reinforcing element extending through the elongated shaft of the catheter to prevent significant elongation or failure of the catheter and a traction member for assisting in the resistance to substantial tensile stresses. The balloon dilatation catheter also includes an expandable means between the balloon and catheter shaft to extend the length of the balloon when it is deflated. The extension of the deflated balloon prevents the balloon from bunching up and interfering with the withdrawal of the balloon through the working channel of the cystoscopic sheath upon the completion of the dilatation. The catheter has a marker for easy visualization so that the balloon can be positioned reliably and a tip construction so that the catheter can be advanced into the bladder safely.