Impressed by numerous observations that diphtheria is relatively infrequent in tonsillectomized persons, Schick and Topper1 of New York studied the effect of tonsillectomy on the production of immunity to diphtheria. They reported that among 100 children who were susceptible to diphtheria, as determined by a positive Schick test just before the operation, 82 per cent gave a negative reaction when retested six months after tonsillectomy. This percentage held true for children under 6 years of age as well as for the older group of children from 6 to 12 years. These authors believe that only a small percentage of a control group could be expected to give negative reactions to the Schick test in a like period of time. The normal expectancy of negative reactions in children, according to the combined figures of Park and Zingher, von Groer and Kassowitz (as presented by Schick and Topper), increases from 16.8