Summary It might be re-emphasized that bacterial chemotherapy has revolutionized the prognosis and treatment of certain acute beta hemolytic streptococcus infections. There is already reason to believe that the advent of chemotherapy has ushered in a period of therapeutic advance even greater than that which marked the introduction of diphtheria antitoxin forty years before. In general, patients will always have a better prospect of recoveryif treated scientifically. In addition to having the requisite knowledge of clinical and laboratory aspects of disease processes, it is necessary to be fully conversant with the pharmacology of the individual chemotherapeutic substances. Because of the lifesaving results in certain severe streptococcic diseases or in serious complications of the less severe infections, the clinician is justified fully in starting chemotherapy on the basis of clinical diagnosis without waiting for the bacteriologic reports. On a pragmatic basis, one patient cured gives greater satisfaction than a number of fully investigated dead ones. Severe illness justifies the incurring of certain risks, and therefore the fear of toxic manifestations must not be allowed to interfere with the employment of full and effective dosage. The new method, however, is still subject to many limitations, and westill do not possess perfect chemical agents that will destroy the bacteria while leaving the body cells completely unaffected. Therefore, in the treatment of a mild disease, or in attempts at prevention, there is hardly justification in incurring greater risks than are present in the condition itself. One does not use a duck gun on sparrows. It even may be conceded that with newer studies and developments in the field of chemotherapy, many of the present most sanguine hopes from therapy and prophylaxis may be realized, but we lay ourselves open to criticism if we depart from scientific method and critical approach. It would seem that at this time, members of a group like ours may well grasp whatever opportunity is afforded us to set up controlled clinical studies of sufficient size and scope to give the profession trustworthy indications.