Crohn's disease and ulcerative colitis are the major entities of inflammatory bowel diseases (IBD). IBD is a clinical diagnosis, which is supported by endoscopic, histologic, radiologic, sonographic and laboratory findings. IBD are not restricted to the GI-tract but are instead systemic diseases that often involve extra-intestinal manifestations. Aim of the rational medical therapy is the induction and maintenance of a steroid-free remission. The medical therapy depends on the severity, activity and extent of disease as well as the disease course of the patient. There is the dire necessity for an individualized therapeutic concept as the natural disease course differs between the patients.