When conventional modalities (external beam irradiation and chemotherapy +/- resection) are used in the treatment of locally advanced gastrointestinal malignancies, although useful palliation can be achieved in many patients, local control and long-term survival are infrequent. In recent trials, investigators have used fractionated external beam doses of 4500-5000 rad in 180 rad fractions in combination with irradiation boost techniques of intraoperative electrons, or intraoperative or transcatheter brachytherapy (+/- chemotherapy and resection). With colorectal and biliary cancer, both local control and long-term survival appear to be improved, compared to results achieved with conventional treatment. With pancreatic cancer, an apparent improvement has been noted with local control and median survival, but long-term survival has not been altered. For partially resected gastric cancer, the use of intraoperative irradiation has yielded five year survival rates of approximately 20%. With unresectable or residual gastric cancer, accelerated fractionation alone or in combination with chemotherapy has yielded excellent local control, but patients have died as a result of abdominal failure or lung metastases. Prevention of abdominal failures will be necessary to improve long-term survival with pancreatic and gastric cancer. Randomized trials by site are needed to determine if the observed differences seen in prospective nonrandomized trials are real or due to differences in case selection.