[en] Intraoperative radiotherapy (IOR) of unresected advanced cancers of the biliary system and pancreas improves both subjective and objective symptoms. IOR with radical resection, however, provided excellent local control of the tumor bed and significantly prolonged survival time. The optimal single dose of IOR appears to be 25 to 30 Gy. Bleeding and stenosis of the stomach and duodenum were observed but were prevented by keeping the organs out of the radiotherapy energy field. IOR combined with radical resection is concluded to be an effective method of treating selected cases of cancer of the biliary system and pancreas. (author)