The temporary radioisotope stent catheter system of the present invention includes a temporary radioisotope stent that is situated at a distal portion of two, co-axially situated, thin-walled tubes. The catheter system can be delivered into a vessel of a human body either as a stand-alone device or it can be used in conjunction with an elongated cylindrical sheath which is a form of delivery catheter. If used as a stand-alone device, the temporary radioisotope stent is first percutaneously advanced through a guiding catheter and is then placed at the site of a stenotic dilatation. An operating means located at a proximal portion of the catheter system is then used to increase the diameter of the temporary radioisotope stent to be approximately equal to the inside diameter of the dilated stenosis. The temporary radioisotope stent is then retained at that position for an irradiation time period that is determined by the level of radioactivity of the stent, by the diameter of the dilated stenosis, and by the dose of radiation that is prescribed for application to that portion of the artery. At the conclusion of the irradiation time period, the operating means at the proximal portion of the catheter system is used to decrease the diameter of the temporary radioisotope stent to its minimum value, and then the catheter system is removed from the patient's body.