The aim of this study was to assess the value of radiotherapy, and especially intraluminal brachytherapy, after resection of hilar cholangiocarcinoma by analyzing long-term complications and survival. Between 1983 and 1998, 112 patients underwent resection of a hilar cholangiocarcinoma. Of the 91 patients who survived the postoperative period, 20 patients had no additional radiotherapy, 30 patients had only external radiotherapy (46 +/- 11 Gy), and 41 patients had a combination of external (42 +/- 5 Gy) and intraluminal brachytherapy (10 +/- 2 Gy). Overall, 88% of the patients had late complications, with a significantly higher rate of complications occurring among patients receiving external beam irradiation and brachytherapy. Second to abdominal pain (56%), cholangitis (49%) was the most frequent complication and occurred significantly more often in patients who had received brachytherapy. Retrograde bile leakage after closure of the temporary jejunostomy was a troublesome complication in 24% of patients treated with brachytherapy. Overall median survival after treatment with adjuvant radiotherapy was longer than after resection without additional radiation (24 months versus 8 months, respectively). There was, however, no significant benefit from the use of intraluminal brachytherapy. In conclusion, additional radiotherapy after resection of hilar cholangiocarcinoma significantly improved survival and is recommended by giving external beam irradiation but not intraluminal brachytherapy.