IN THE YEAR 1939, Thomas and France1 and Coburn and Moore2 reported their use of sulfanilamide in preventing the recurrence of rheumatic fever. Since then, many other reports have confirmed their results and have shown that other sulfonamides are similarly effective. In 1940, at the Children's Heart Hospital, we began to administer sulfanilamide to a small number of patients. During the following decade, we continued this administration, using various sulfonamides and each year increasing the number of children receiving the drug. Then, following Massell's3 report, we replaced the sulfonamides with orally administered penicillin for two years. The results of these studies concur with those already published and are therefore not unusual. However, these results represent 12 years of administration and observation. Moreover, they afford an indirect comparison of the efficacy and toxicity of the sulfonamides versus orally administered penicillin. For these reasons, they may be of special