Fifty-one patients with carcinoma of the extrahepatic bile ducts (EHBD) received radiation therapy between January 1980 and December 1988. The location of the tumors was: proximal third, 20 patients; middle third, 23 patients; distal third, 3; diffuse, 5 patients. Thirty-six patients underwent surgery with complete gross resection in 14 (10/14 with positive margins), incomplete gross resection in 12 and only biopsy in 10. Fifteen patients had only biliary drainage without laparotomy after cytologic diagnosis of malignancy in 11/15. Radiation therapy was done with curative intent after complete or incomplete resection (n = 26) and it was palliative in patients who had no resection or only biliary drainage (n = 25). Twenty-five patients received external radiation-therapy (ERT) alone to the tumor and lymph nodes (mean dose 45 Gy/2 Gy per fraction for cure, 35 Gy/10 fractions for palliation), 8 patients had only iridium-192 (192Ir) implant (50-60 Gy at a 1 cm radius for cure, 30 Gy for palliation), 17 patients had both ERT + 192Ir (ERT 42.5 Gy + 192Ir 10-15 Gy for cure; ERT 20 Gy/5 fractions + 192Ir 20-30 Gy for palliation) and one intra-operative irradiation + ERT. The overall survival for the entire group was 55, 28.5 and 15% at 12, 24, 36 months and median survival 12 months. Median survival was 22 months in patients treated with curative intent and only 10 months after palliative treatment (p 0.03). Among patients who had curative treatment, median survival was 27.5 months after complete gross resection and 13 months after incomplete gross resection (p 0.045).(ABSTRACT TRUNCATED AT 250 WORDS)