Corticosteroids and 5-amino salicylic acid (5-ASA) are established therapies in the induction of remission and in maintenance of remission in patients with ulcerative colitis. 5-ASA exists in different delivery systems, however, clinical studies directly comparing these preparations exist only in very limited numbers. When analyzing placebo-controlled or comparative studies it is clearly evident that 5-ASA is superior to placebo in both induction of remission and maintenance therapy. In maintenance therapy prodrug compounds (sulfasalazine, SASP) seem to be marginally better compared to 5-ASA slow release preparations. Direct comparison of the newer 5-ASA preparations is not possible because of limited data. Theoretical considerations based on the different principles of slow release are also questionable since the intraluminal pH or intestinal motility may be disturbed in IBD.