If we inject 0.1 cc. of the filtrate of a broth culture of typhoid bacilli intracutaneously in the arm of a human being, there appears in from 12 to 24 hours a reaction similar to that produced by the injection of Streptococcus scarlatinae toxin. The reaction fades after 24 to 48 hours, but may leave a slight pigmentation. This reaction has been produced with filtrates of 1, 2 and 5-day cultures, being approximately the same with all. The filtrate was obtained by passing the culture through either Berkefeld W, N or V filters, but usually the N filter was used. Several strains of the organism gave similar results. The filtrates varied in activity, and we have obtained reactions with dilutions of even one to two thousand. Usually a dilution of 1 to 500 was used. The reactions produced in normal subjects (who neither had had typhoid fever nor were ever immunized against typhoid fever) are very variable, and while reactions can be produced in all, the area and intensity of the response seem to be individual characteristics. In individuals who had been immunized against typhoid fever, either recently or several years previously, the reactions were similar to and quite as varied as those in the normal subjects. The same statement holds true of individuals who had had typhoid fever some years previous to the injections. No evidence of any ability to inhibit the local reaction was noted in persons who had had typhoid fever, or who had been immunized against typhoid fever. In individuals having typhoid fever, the reaction to the injection of the filtrate was markedly diminished (as compared with weakly reacting normal inclividuals) or was negative.