The natural history of Crohn's disease is one of remission and recurrence. Until recently there has been no evidence that medical therapy can alter the pattern of recurrence. Recent large multicenter trials have demonstrated that the aminosalicylates may be effective in maintaining remission. Preliminary studies have also suggested that biochemical investigations may identify patients at high risk for recurrence. Additional studies that combine such predictive models with double-blind, placebo-controlled clinical trials are warranted.