The chronic or recurrent immunologic and inflammatory response in ulcerative colitis and Crohn's disease may be initiated from the gut lumen. Deviation of gut contents away from the inflamed area, bowel rest, or the use of liquid diets appears to benefit Crohn's disease. The relative effects of complete bowel rest, or an elemental, hydrolysed, or polymeric liquid diet have not yet been established. Measures to alter the lumenal bacterial flora, including antibiotics, require further study. The use of corticosteroid drugs can be improved by the use of poorly absorbed or rapidly metabolized compounds. Aminosalicylates are effective in ulcerative colitis but require further study in Crohn's disease. Immunosuppressive drugs are valuable not only for a steroid sparing effect but also for control of chronic inflammation. New treatments designed to reduce inflammation are promising but will need to have high potency and an effect at the earliest stages of inflammation before a large number of different inflammatory mediators are released.