Mucosal proctectomy with J-pouch construction and ileostomy were performed on eight patients (age range from 4 to 18 years), five with ulcerative colitis and three with familial polyposis coli. Complications of the first stage included transient neuropraxia of the lateral popliteal nerves, partial dehiscence of the ileoanal anastomosis and prolapse of the loop ileostomy. The ileostomy was closed 2 to 7 months after initial surgery and was associated with four further complications: enterocutaneous fistula at the ileostomy site, early and late bowel obstruction and pouchitis. Stool frequency decreased as the length of follow-up increased: 3 to 4 stools daily for three children at 2 years postoperatively compared with 4 to 10 stools daily in all children 1 month after surgery. Functional results were satisfactory and all patients preferred the J pouch to an ileostomy.