A chemical for the treatment of infections, such as bacilliary dysentery, which are limited to the gastrointestinal tract should have certain properties. It must dissolve in the bowel content in a concentration adequate to inhibit the multiplication of, or to kill, pathogenic organisms and must be harmless to the human or animal host. No intestinal antiseptic has, in the past, fulfilled these requirements. The use of the sulfonamide drugs has become firmly established in the treatment of various infections, but the rapid and complete absorption of these chemicals from the gastrointestinal tract has made them valueless in the therapy of local enteric infections. The report by Marshall, Bratton, White and Litchfield,1 describing the properties of sulfaguanidine, the analogue of sulfathiazole and sulfapyridine, was received, therefore, with great interest. This drug was found to be soluble in water in amounts sufficient to cause adequate bacteriostasis of intestinal pathogens but was