During the past three years an ever increasing volume of favorable reports1 have emanated from Europe concerning the use of para-aminobenzenesulfonamide and its derivatives in the treatment of infections due to beta hemolytic streptococci. During the past few months we have had the opportunity of employing these new specific chemotherapeutic agents in the treatment of experimental and clinical infections produced by beta hemolytic streptococci. We have discussed our preliminary observations in a previous report.2 In this communication we shall describe briefly the action of the compounds which we have tested and detail our experiences in the clinical use of para-aminobenzenesulfonamide and its derivatives in the treatment of human beings with infections due to hemolytic streptococci. EXPERIMENTAL OBSERVATIONS In the course of our investigations we have used two samples of para-aminobenzenesulfonamide, one supplied to us by E. I. DuPont de Nemours and Company and the other by the Winthrop