Crohn's recurrence is the appearance of objective signs defined radiologically, endoscopically or pathologically of Crohn's disease in the bowel of a patient who has previously had a resection of all macroscopically diseased tissue. New lesions can be visualized endoscopically within weeks to months after ileal resection and ileocolonic anastomosis in the neoterminal ileum. The evolution of these lesions mimics the natural history of ileal Crohn's disease at the onset. If we are able to prevent recurrence of early lesions we would probably interrupt the natural course of the disease. The drugs tested until today include different 5-ASA formulations, metronidazole and budesonide. 5-ASA seems to have a limited protective effect. High dose metronidazole started immediately after surgery decreases endoscopic and symptomatic recurrence rates but is associated with a lot of side effects. Budesonide 6 mg/day o.m. reduces endoscopic recurrence after one year only in patients operated upon for inflammatory activity. Studies with immunosuppression for recurrence prevention are currently underway. Thus, today 5-ASA-formulations are recommended as general pharmaco-prophylaxis.