Assessment of the nature, location and extent of the disease, disease activity and the intestinal and extraintestinal complications and manifestations is an essential prerequisite in the treatment of inflammatory bowel disease. Corticosteroids, sulfasalazine (SASP) and rectal administration of 5-aminosalicylic acid (5-ASA) are effective in the treatment of ulcerative colitis. Oral 5-ASA in the form of a slow-release preparation is probably also effective. Rectal SASP or 5-ASA in addition to corticosteroids is indicated in distal colitis. In severe pancolitis oral or intravenous corticosteroids are required, whilst in less severe forms SASP or 5-ASA can be used. However, the safety of 5-ASA over longer treatment periods has yet to be verified. Surgery is indicated in colitis refractory to maximal treatment over several months. Apart from parenteral or enteral nutrition, treatment with prednisolone is effective in acute exacerbations of Crohn's disease. SASP is possibly effective in colonic disease. The role of 5-ASA has yet to be defined. A prednisolone-induced remission can be maintained by means of low doses of prednisolone. SASP is probably not effective, whilst with 5-ASA conclusive data are missing. Metronidazole and azathioprin are considered to be reserve drugs and can be used in the treatment of fistulae or in order to cut down the dosage of prednisolone during remission. Substitution with vitamins and trace elements is necessary in a large number of patients with Crohn's disease.