THIS study was designed to determine whether lincomycin hydrochloride monohydrate is superior to penicillin G potassium in treating recurrent streptococcal illnesses or the streptococcal carrier state or both. In our first study on the comparative effectiveness of lincomycin and penicillin against β-hemolytic streptococci, we showed that the treatment of these infections with lincomycin resulted in fewer bacteriologic recurrences than was the case when penicillin was used. To our surprise no "carriers" of β-hemolytic streptococci occurred among 100 children treated with lincomycin whereas 12 "carriers" occurred among 102 children treated with penicillin.1 The experience of Martin F. Randolph, MD, and Raymond M. L. De Haan, MD (unpublished data) with lincomycin was similar to ours in that carriers were only infrequently found after lincomycin treatment of the initial streptococcal illness. This suggested that lincomycin might therefore be more effective than penicillin in one of the most common therapeutic problems faced by the