Proximal bile duct carcinoma (Klatskin tumour) is infrequent and difficult to treat. In principle, surgery is indicated. The usefulness of irradiation after resection is controversial in the literature. This article describes the experiences gained in the Academic Medical Centre of Amsterdam with pre- and postoperative irradiation of resectable Klatskin tumours. Preoperative irradiation (10.5 Gy) is administered to devitalize detached tumour cells in the bile, to prevent implantation metastases after resection. Postoperative irradiation has been administered since 1986 according to protocol. An analysis of 71 patients, of whom 48 had been irradiated after resection while 23 had not, showed a statistically significant prolongation of survival in the group irradiated postoperatively. Radiotherapy was administered externally (55 Gy) or in combination with internal radiotherapy (45 Gy external, 10 Gy internal). For internal irradiation, the source of radiation (Iridium-192) was introduced along the bile duct anastomoses via the soma formed by the blind end of the Roux-Y jejunal loop used for bile duct reconstruction. Since internal irradiation in combination with external irradiation caused more complications, while there was no difference of survival from patients only irradiated externally, the complete postoperative irradiation is currently being given from the outside. Pre- and postoperative irradiation may contribute to the success of the treatment of the resectable Klatskin tumour