Up to 20-30% of patients treated with sulphasalazine experience a variety of adverse effects, principally due to the carrier moiety sulphapyridine. In the last decade there has been a major drive to develop a new generation of 5-aminosalicylic acid (5-ASA) and 5-ASA-related drugs which not only have a high efficacy but are also devoid of the unwanted side-effects of sulphapyridine. Various forms of 5-ASA have been evaluated in ulcerative colitis and appear to be effective orally in preventing relapse and topically in the treatment of active distal colitis. More recently, topical 4-ASA has been found to be useful for the treatment of distal colitis with the advantage of better stability and lower cost compared with 5-ASA. In the foreseeable future it seems likely that these new aminosalicylic acid derivatives will become the drugs of choice in the treatment of inflammatory bowel disease and largely replace sulphasalazine.