PURPOSE: In rectal cancer, it is known that the postoperative radiotherapy is an effective way for reducing locoregional recurrence, especially if accompanied with concurrent chemotherapy. However, toxicity to small bowel was one of the major limitations to perform full-dose radiotherapy. For overcoming this problem, abdominopelvic omentopexy, which separates the small bowel from the pelvic cavity, was developed. This study analyses the acute and chronic complications related to the partitioning of the pelvic cavity and subsequent postoperative radiotheraphy. METHODS: From January 1990 to September 1999, medical records of 127 patients with rectal cancer who underwent abdominoperineal resection were retrospectively reviewed. Seventy-one of these patients belonged to stages B2 through D according to the modified Astler-Coller classification and underwent adjuvent chemoradiation therapy, and abdominopelvic omentopexy was performed in thirty- three patients. We compared postoperative radiotherapy complications between abdominopelvic omentopexy group and non-abdominopelvic omentopexy group. After abdominoperineal resection, the greater omentum covers whole small bowel like apron. The lateral edges are attached to both lateral peritoneal wall with continous running suture. The lower margin is sutured to the parietal peritoneum of the posterior abdominal wall at the level of the aortic bifurcation. The pelvic reperitonealization was carried out in whole patients. RESULTS: In the group of radiotheraphy with abdominopelvic omentopexy, six patients showed signs of acute radiation enteritis, whereas no case of chronic radiation- induced enteropathy was observed. Other complications were postoperative ileus (three patients), urinary problems (four patients), radiation dermatitis (ten patients), and radiation-induced leukopenia (three patients). In the group of radiotheraphy without abdominopelvic omentopexy, 7 out of 38 patient developed symptom and sign of radiation- induced chronic complication. The chronic complication rate is significantly lower in the omentopexy group than in the non-omentopexy group (P=0.0089). CONCLUSIONS: Abdominopelvic omentopexy is effective for preventing the late sequela of radiation-induced enteritis.