The evolution of the recurrence of Crohn's disease after ileal resection and ileocolonic anastomosis closely mimics the natural history of the disease. The pattern of disease does not change after resection compared with that before surgery. New lesions develop within weeks to months after resection in the neoterminal ileum and the severity of these early lesions determine when symptoms and complications recur. This model of early recurrence of Crohn's disease lesions is rather new and drug prevention studies are scarce. A 3-month course of metronidazole (20 mg/kg) has been shown to decrease the rate of severe recurrence. Data on 5-aminosalicylic acid therapy are controversial. Claversal seems to be ineffective in preventing recurrence, whereas Pentasa 3g/day and Asacol 2.4g/day decreased the rate of endoscopic recurrence, with less symptomatic recurrence observed with the latter drug. Promising drugs for the prevention of recurrence include budesonide, a new 'topically acting' glucocorticosteroid, and immunosuppression using azathioprine or 6-mercaptopurine. Large multicentre trials of these drugs are currently underway. In the meantime, early endoscopy after ileal resection is only advocated for clinical studies as, at present, this will not influence therapy in most patients.