BACKGROUND & AIMS: Standard corticosteroid therapy for Crohn's ileitis induces symptom relief without improvement of endoscopically visible lesions. In this study, the effect of azathioprine therapy on the inflammatory lesions in the neoterminal ileum of patients with severe postoperative Crohn's recurrence was examined. METHODS: Macroscopic ileal lesions were studied endoscopically or radiologically after at least 6 months of azathioprine therapy after complete weaning of corticosteroids. All patients who underwent an ileocecal resection for Crohn's disease at our institution between January 1989 and December 1993 and who subsequently developed severe recurrent ileitis treated with azathioprine were included. RESULTS: Of the 19 patients treated with azathioprine for recurrent ileitis, 15 could be reevaluated by endoscopy or radiological examination. The therapy resulted in induction and maintenance of clinical remission in all 15 patients, at least 6 months after complete weaning of the corticosteroids. Complete macroscopic healing of the neoterminal ileum was observed in 6 of 15 patients, near-complete healing with only superficial erosions remaining in 5 of 15 patients, partial healing in 3 of 15 patients, and unchanged inflammatory lesions in 1 patient. CONCLUSIONS: It is concluded that azathioprine leads to mucosal healing in severe recurrent Crohn's ileitis and may be the treatment of choice in this indication.