Abstract: A method for preventing restenosis after angioplasty comprises internally radiating the treated portion of the lumen to prevent restenosis of the enlarged lumen portion. A device useful for radiating the treated portion comprises an elongated flexible catheter with radioactive means located in a distal section of the carrier. Stiffening elements are located along the length of the catheter to enable the catheter to be pushed through the tortuous segments of coronary or peripheral vasculature without crimping.