Late in the summer of 1941 sulfadiazine was supplied to the Milwaukee Children's Hospital for clinical investigation of its use in treatment of and its effect on infants and children.1 At that time there were only a few articles available in the literature on this new sulfonamide compound and most of them related to its use experimentally in animals. There were several articles which reviewed its use for human patients, and most of these reports dealt glowingly with the absence of toxic effects and the relative nontoxicity of this new drug.2 However, there was little to draw from as to its efficacy against the usual infections seen in a children's hospital or as to the dosage to employ for consistently satisfactory blood levels. With this in mind, the present study was undertaken, and the results and conclusions were presented in an abbreviated form before the Milwaukee County Medical