The ideal intestinal antiseptic should be poorly absorbed from the alimentary canal and should have strong antibacterial local action. A compound, succinylsulfathiazole.1 which has properties approximating these specifications, has been synthesized by Moore and Miller.2 The experimental determination of the value of succinylsulfathiazole as an intestinal antiseptic and its early clinical use were described by Poth, Knotts, Lee, Inui, Chenoweth and Welch, Mattis and Latven.3 The drug has been used for about one year and has been given to approximately 250 patients in this clinic. These cases have been studied closely for evidences of hemocytologic changes and accumulation of the drug in the blood. The total quantity of drug excreted in the urine was determined in the majority of these cases, and the alteration of the intestinal flora was assayed by quantitative bacteriologic study. Within one to seven days of the institution of sulfasuxidine therapy the feces