The treatment for patients with Crohn's disease of moderate to severe activity includes traditional drugs, such as corticosteroids, the primary therapy for these forms of disease, able to induce the remission of symptoms in a high percentage of patients. Because of the side-effects produced by systemic steroids, a new glucocorticoid derivative, budesonide, which acts locally in the mucosa, has recently been introduced with positive results. On the assumption that intestinal bacteria play a role in the causing Crohn's disease symptoms, antibiotics are often used in the treatment of active phases, as an alternative to or in association with steroids. The most widely employed antibiotics are metronidazole and ciprofloxacin. Immunosuppressors, such as azathioprine and 6-mercaptopurine, are useful for the treatment of chronic active disease and for maintaining remission, but they have only a marginal role in the therapy of an acute flare-up of Crohn's disease. Methotrexate acts more rapidly and its use in patients with active disease resistant to standard therapy is of interest. The discovery of biological agents represents a new era in the management of patients. To date, infliximab is the more extensively studied biological therapy in the treatment of Crohn's disease and clinical studies have demonstrated its efficacy in inducing remission of refractory disease.