Several factors are important for the pathogenesis of bacterial intestinal disease: 1. Colonisation of the intestine; 2. exo(= entero)toxin production without penetration into the intestinal wall; 3. invasion of the intestinal wall with or without (?) simultaneous formation of enterotoxin. These factors are of different importance for the various infective agents. Whereas cholera is exclusively caused by an enterotoxin, this is of minor importance for the pathogenesis of Shigella dysentery. The enterotoxins of Vibrio cholerae, Escherichia coli, and Shigella dysenteriae 1 have been intensively studied. Additional enterotoxic substances have been demonstrated in other gramnegative organisms (Salmonella typhimurium, Yersinia enterocolitica, Klebsiella pneumoniae, Vibrio parahaemolyticus, Aeromonas hydrophila), which, however, are not yet characterized sufficiently. Future studies will aim to the elucidation of the structure and function of these toxins on the molecular level, and their importance for the pathogenesis of intestinal disease.