Book excerpt: Diseases of the digestive system have a higher morbidity rate than any other group of disorder. There is a growing body of evidence that the immune system participates in the pathogenesis of a wide range of these diseases, including peptic ulcer disease and the gastropathy induced by nonsteroidal anti-inflammatory drugs (NSAIDS). For these reasons, efforts to develop novel therapies for digestive diseases are increasingly focused on the immune system. This volume reviews the immunopharmacology of the gastrointestinal tract at four distinct levels: Immunomodulation at a cellular level Cellular targers for immunomodulating drugs Specific classes of inflammatory mediators Utility and mechanisms of action of glucocorticoids in the treatment of diseases of the gastrointestinal tract.