We reviewed the findings on 169 contrast enema examinations in 92 patients with late radiation injury of the rectum and sigmoid colon, encountered over an 11-year period. The diagnosis was made by rectosigmoidoscopy in all patients. The limitations and pitfalls of both examinations were studied. The mean interval between radiotherapy and diagnosis was 1.7 years and the mean follow-up period was 3.5 years. The main radiological features varied from normal findings (15% of the initial examinations) to decreased distensibility of the bowel wall, intestinal fixation, mucosal and contour abnormalities, ulceration, stenoses and fistula formation. During follow-up, the number of all pathological findings increased. Pre-stenotic dilatation of the descending colon was always absent. The contrast enema examinations and endoscopies were found to be complementary. The barium enema showed the extent of the disease and accurately identified stenoses and fistulas, but underdiagnosed ulceration and overdiagnosed malignancy. Endoscopy allowed unequivocal detection of mucosal damage, especially ulceration, and was accurate in showing stenoses but sometimes failed to demonstrate fistulas. Moreover, in 25% of examinations it was impossible to examine the entire abnormal area.