Ileoanal anastomosis is a surgical procedure performed in patients with ulcerative colitis. In a small number of patients operated on for ulcerative colitis, Crohn's disease occurs in the reservoir, mimicking pouchitis, and may lead to pouch excision and to a permanent terminal ileostomy. Two patients with recurrent Crohn's disease in the reservoir after ileoanal anastomosis were treated with azathioprine for 18 and 24 months, respectively. Azathioprine induced a complete clinical and endoscopic remission. These two observations suggested that immunosuppressive drugs were a good option for permanent ileostomy in cases of recurrence of Crohn's disease in the reservoir after ileoanal anastomosis.