Pelvic radiation remains the mainstay in the treatment of many malignancies. Chronic radiation injury represents an obliterative endarteritis. The purpose of our experiment was to investigate the chronic changes in blood flow that occurred in a model of pelvic radiation. Also, we investigated the potential benefits of an elemental diet, sodium meclofenamate, and vitamin A within the radiated large and small bowel. Female Sprague-Dawley rats, 200-250 g, were anesthetized and received 900 rads once a week for 5 weeks for a total of 4500 rads. Group B received sodium meclofenamate, group C elemental diet, and group D vitamin A. Group A received radiation only where control animals (group E) received anesthesia but no radiation. All animals were given treatments during the course of radiation therapy only. Blood flow was determined within the terminal ileum, proximal jejunum, and distal colon 1 week, 5 weeks, 6 months, and 1 year postradiation therapy. Blood flow was determined by strontium-labeled 15-μ microspheres. Results showed that radiation resulted in an increase in blood flow within the terminal ileum at 1 week postradiation of approximately 175% when compared to controls. Blood flow then decreased (59%) when compared to controls at 5 weeks and increased (141%) again at 6 months when compared to controls. No change in blood flow was noted at 1 year postradiation therapy. An elemental diet and sodium meclofenamate prevented these changes in blood flow at each of these time points. No change in blood flow was seen at any of the time points measured within the jejunum or colon.