The relative number of viable Eberthella typhosa being excreted by chronic carriers and clinical cases of typhoid was detd. by quantitative cultural tests. The drug was given in doses adequate to maintain a blood level of 8 to 12 mg. %. Under treatment there was consistently a prompt and marked reduction in the discharge of E. typhosa. On withdrawal of medication from chronic carriers, the number of organisms returned to the pre-treatment levels, but bacteriological recurrences were unusual in cases. The clinical significance of this treatment could not be detd. in the small series of cases observed.