From May 1978 to December 1989, 54 patients with pancreatic carcinoma underwent electron beam intraoperative radiotherapy (IORT). Three died of preoperative complications within a month. In 19 patients, liver metastasis and/or peritoneal dissemination became obvious at laparotomy. They therefore underwent IORT with palliative intent. Relief of pain was obtained in 12 of the 14 patients with pain (85.7%), although three of them were treated in combination with splanchnic nerve block. Thirty-two patients with localized carcinoma underwent IORT with curative intent (total tumor resection in 6, partial resection in 6, and no tumor resection in 20). With additional IORT treatment, their survival was significantly (p less than 0.05 during the 18th month) longer than that of 40 patients without IORT (total tumor resection in 13, partial resection in 9, and no tumor resection in 18). Among the patients without tumor resection, the 20 patients who underwent IORT survived significantly (p less than 0.05 during the 7th month) longer than the 18 patients who did not. Twelve patients who underwent total pancreatectomy died earlier than the 23 patients treated with IORT in combination with partial tumor resection or no tumor resection (not significant). In 26 patients with partial tumor resection or no tumor resection, either additional external irradiation or IORT using a small field within a large field significantly (p less than 0.05 during the 7th and 8th month) improved survival compared with IORT using a single field. Of the 20 patients without tumor resection, relief from pain was obtained in 18 of 19 patients with pain (94.7%), although two of them were treated in combination with splanchnic nerve block. In terms of adverse effects possibly caused by IORT in 26 patients who survived longer than 6 months, gastrointestinal problems were serious in several (gastric ulcer in 2, duodenal stenosis in 1, gastric ulcer and duodenal stenosis in 1, and duodenal perforation and duodenal ulcer in 1). In conclusion, our experience suggests that IORT can relieve patients of serious pain and improve survival in patients with localized pancreatic carcinoma.