Laboratory1and clinical2studies have shown that penicillin is highly effective against the hemolytic streptococcus. It is more active than sulfonamides in protecting mice against lethal infections with this organism.3There are also a number of reports of hemolytic streptococcic infections which resisted sulfonamide therapy but responded well to penicillin.4Such observations and the lack of toxicity of penicillin have made it the treatment of choice in severe hemolytic streptococcic infections. Direct comparisons of sulfonamide and penicillin therapy in hemolytic streptococcic infections are included in the reports already mentioned. In addition, Plummer and his co-workers5found that hemolytic streptococci could no longer be found in the majority of throat cultures taken from patients with pharyngitis or tonsillitis after forty-eight hours or more of intramuscular treatment with 15,000 units of penicillin every four hours. The organisms frequently reappeared and symptoms relapsed, if the treatment was carried