From June 1994 through September 1995, 17 patients with gynecologic cancer were entered into a feasibility study using elemental supplements (ES) during the course of pelvic radiotherapy. The level of compliance with the ES regimen was evaluated by assessing sachet counts and patients' weekly diaries. Diaries were also used to assess compliance with a modified diet program. Bowel function in 45 patients receiving radiotherapy outside this study was assessed concurrently. All patients were reviewed weekly to record bowel function, which was also recorded 1 year after radiotherapy. After treatment of all patients the grade, duration of enteritis, need for antidiarrheal agents, and the likelihood of resolution at 1 year after radiotherapy were analyzed. The study used compliance with the ES regimen as its primary endpoint. Compliance with the ES regimen was achieved in 76.5% of patients, and compliance with the modified diet was achieved regardless of whether the ES was tolerated. Patients not complying with the ES, or who did not receive ES, had higher grade diarrhea, which was longer in duration and was less likely to have resolved than patients in the compliant group. Elemental supplements are well tolerated when taken during a course of pelvic radiotherapy and cause a mild diarrhea, which resolves after treatment has been discontinued. The lack of enteritis 1 year later in patients who complied with ES suggests that reducing the grade of acute enteritis might influence the appearance of later bowel effects.