Sulfasalazine continues to be a common treatment for active Crohn's disease. It has been shown to be more effective than placebo in patients with colonic disease and in patients without prior surgical resection. There is no clear clinical evidence for its use as maintenance therapy in quiescent Crohn's disease; nevertheless, it is widely used to prevent symptom recurrence in patients whose active disease responded to sulfasalazine. In a few preliminary controlled studies, mesalazine has been shown to be superior to placebo in the treatment of active Crohn's disease. Until recently, the results of trials of mesalazine as maintenance therapy in quiescent Crohn's disease were equivocal but promising.