Patients who have undergone straight ileoanal pull-through operations without a reservoir in adult life frequently have unsatisfactory results. Operative correction of this problem has been difficult. We propose a new operation that preserves the ileoanal anastomosis, constructs a reservoir, and has resulted in good restoration of bowel function in three patients. The operative procedure consists of division of the ileum 30 cm above the dentate line. The distal ileum is then folded over itself so that the point of division reaches into the pelvis, between the rectal muscular cuff and pulled-through ileum, to a point just proximal to the dentate line. The two limbs of ileum are connected using a stapler, completing the reservoir construction. The proximal divided ileum is anastomosed, end-to-side, to the pouch. A protective ileostomy that can be closed in three months is constructed.