At 1 year after a first resection, up to 80% of patients show an endoscopic recurrence, 10-20% have clinical relapse, and 5% have surgical recurrence. Smoking is one of the most important risk factors for postoperative recurrence. Preoperative disease activity and the severity of endoscopic lesions in the neoterminal ileum within the first postoperative year are predictors of symptomatic recurrence. Mesalazine is generally the first-line treatment used in the postoperative setting but still provokes considerable controversy as to its efficacy, in spite of the results of a meta-analysis. Immunosuppressive treatment (azathioprine, 6-mercaptopurine) is based on scant evidence but is currently used as a second-line treatment in postsurgical patients at high risk for recurrence, with symptoms or with early endoscopic lesions in the neoterminal ileum. Nitroimidazole antibiotics (metronidazole, ornidazole) are also effective in the control of active Crohn's disease in the postoperative setting. Given their known toxicity, they may be used as a third-line treatment as initial short-term prevention therapy rather than in the long term. Conventional corticosteroids, budesonide or probiotics have no proven role in postoperative prophylaxis. Infliximab has not as yet been studied for use in the prevention of relapse after surgery. [Ed.]