Inflammatory bowel diseases (IBD) are chronic, often life-long diseases of the small and large bowel of unknown aetiology and of pathogenesis only partly known. The results of a long-term drug therapy are not satisfactory due to the limited efficacy and frequent adverse side effects. Nevertheless, for patients with mild to moderate active form of disease, the 5-ASA and glucocorticosteroids remain the most important drugs to induce remission and use as maintenance treatment. Therapy with 5-ASA has reduced relapse rates by about 50 % over 1-year follow-up period. 80 % of patients with IBD initially respond to corticosteroids, the long-term benefit of corticosteroid therapy is not satisfactory. For many patients there is a great promise using of immunosupressives. The most frequently used immunosupressives are the antimetabolites azathioprin and methotrexate.