Cholangiocarcinoma at the confluence of the hepatic ducts (Klatskin tumor) is a slowly growing malignancy with early onset of symptoms and poor outcome since surgery allows radical resection in only a minority of cases. Percutaneously placed biliary stents offer a good palliation, but tend to obstruct after 6-8 months; then, retreatment requires exchange of the endoprosthesis or establishment of a permanent external-internal biliary drainage which offers, in some patients, a relatively long survival. Percutaneous intraluminal HDR brachytherapy might be a valid alternative as a definitive therapy or as a method to keep metallic stents patent for a long time. Five patients with hilar cholangiocarcinoma, diagnosed by means of ultrasound, Computed Tomography, percutaneous transhepatic cholangiography and transluminal biopsy, underwent double percutaneous external-internal biliary drainage. Dummy sources were introduced into the drainage catheters to allow dose distribution planning. The stepwise progression of the miniaturized high activity Iridium source inside the applicators, introduced into the drainage catheters, was controlled and monitored by a computer equipped with dedicated software. In the radiotherapy bunker, using the remote loading technique, percutaneous intracavitary high dose rate brachytherapy was delivered at the rate of 750 cGy per fraction, prescribed at 1 cm from the center of the catheter, once a week, for 4 weeks. Nevertheless, only 4 of 5 patients underwent the complete treatment. In one case, radiation treatment was discontinued after the first session because of digestive bleeding from a duodenal ulcer, supposingly as a consequence of the decubitus of a catheter tip. CT demonstrated rapid progression of the disease with neoplastic spread to the omentum and gallbladder wall thickening; a gallbladder malignancy was then suspected and the patient was no more eligibile for brachytherapy. Subsequently, Carey-Coons endoprostheses were inserted to prevent post-actinic strictures and removed after three months. After completing radiation therapy, control cholangiograms demonstrated in all cases improvement of neoplastic strictures. The first two patients we treated show no signs of tumor recurrence at 4 and 1 months, respectively, after endoscopic removal of the stents. The third patient is still bearing 2 Carey-Coons endoprostheses to be removed after 3 months. The last patient with supposingly partial success of bracytherapy, was treated with two Strecker nitinol stents.