Crohn's disease is a chronic inflammatory bowel disease of unknown etiology. Sulfasalazine and the newer 5-aminosalicylates remain the first agents of choice to treat mild to moderate disease and often are effective at high doses as maintenance therapies. Corticosteroids are often required to treat more moderate to severe disease activity, although approximately one-third of patients become steroid-dependent after a steroid-induced remission. Corticosteroids have proven ineffective in maintaining remission and side effects resulting from prolonged exposure preclude their long-term use. Azathioprine and 6-mercaptopurine are effective in the setting of steroid dependence and steroid resistance, as well as for the treatment of perianal and fistulizing complications unresponsive to antibiotics. Crohn's disease commonly recurs following surgical resection, and there is expanding evidence that postoperative prophylaxis with certain antibiotics (e.g., metronidazole), aminosalicylates or immunomodulators may be beneficial in the prevention of disease recurrence following resection. Cyclosporin may benefit patients with severe Crohn's disease or refractory fistulas. Recent trials of newer immunosuppressive agents commonly employed in transplant recipients and ongoing development of a new class of "biologic" agents targeting specific sites in the immunoinflammatory cascade, are expanding the pharmacological armamentarium available to treat certain patients.