Surgery alone often fails to achieve local control in advanced gastrointestinal tumors. With multimodal therapy approaches, both local tumor control and long-term survival appear to be improved. Intraoperative radiation therapy (IORT) is an attempt to achieve higher doses of irradiation while dose-limiting structures are surgically displaced. It has been shown previously that both local tumor control and long-term survival are improved in patients undergoing surgery combined with IORT for both primary and recurrent rectal carcinoma. In advanced gastric carcinoma, IORT has achieved optimistic survival results in a few studies. In locally advanced pancreatic cancer, an apparent improvement in local control has been noted with IORT, but survival has not been prolonged because of a high incidence of both liver and peritoneal metastases. The data concerning IORT for esophageal carcinoma are not yet sufficient to allow judgement.