Despite the obvious benefits of chloramphenicol therapy in typhoid fever,1, 2 there are several problems in this disease which remain to be solved: (1) The present chloramphenicol regimens do not alleviate the toxemia of the disease for at least 36 to 48 hours and fail to eliminate the fever until about the fourth day; (2) relapses of typhoid fever occur in a certain percentage of treated patients3; (3) Salmonella typhosa continues to be shed in the feces for variable periods of time after therapy is begun,2 and (4) the typhoid carrier state when it exists is not permanently benefited by