OBJECTIVE Rectal cancer frequently occurs in patients with familial adenomatous polyposis (FAP) and, in some cases, proctocolectomy and ileal pouch-anal anastomosis (IPAA) can be proposed as an alternative to end ileostomy. This study aimed to assess the results of IPAA for familial adenomatous polyposis complicated by rectal carcinoma. METHODS Postoperative morbidity and bowel function following IPAA were assessed in six patients who had a mesorectal excision for rectal cancer. The functional results were compared with those obtained after IPAA in 134 FAP patients without bowel cancer. RESULTS Carcinomas were located at a mean of 11 cm from the dentate line. There were no postoperative complications. One patient with synchronous hepatic metastases died 6 months after operation and the 5 others were alive without recurrence after a mean follow-up of 29 months. Mean frequency of defecation was 6.5/day (vs. 4.2/day in patients without carcinoma), 86 percent of patients had nocturnal defecation (vs. 50 percent), day and night continence were normal in 66 percent and 33 percent of patients, respectively, compared with 90 percent and 85 percent for IPAA without cancer. Pouch excision was required in one patient for unsatisfactory functional result. CONCLUSIONS IPAA can be safely performed for cancer of the upper rectum complicating FAP, but a poor functional outcome related to mesorectal excision has to be expected.