Recent studies indicate that the normal intestinal flora, an exaggerated reaction of the intestinal immune system and a decreased epithelial barrier function of the gut play an important role in the pathogenesis of Crohn's disease and ulcerative colitis. The medical therapy of inflammatory bowel disease aims to correct these alterations. Aminosalicylates, corticosteroids, immunosuppressants and antibiotics are the four main groups of substances which are currently used for the therapy of inflammatory bowel diseases. Slow release formulation allow specific targeting of 5-aminosalicylic acid to the inflamed sections of the gut; with budesonid a corticosteroid therapy with minimal systemic side effects is possible. Future therapeutic options include specific immuno-modulatory therapy with cytokines or cytokine antibodies. Maintenance therapy may, conceivably, be performed with probiotics or antioxidants. Therefore, despite continued uncertainty about the cause of inflammatory bowel diseases, recent advances nourish the hope for further improvement of the control of disease activity and a better quality of life for patients with inflammatory bowel diseases.