Our purpose in this report is to acquaint the medical profession with the results that have been obtained in the treatment of 500 cases of various infections with penicillin. All these cases have been treated by twenty-two groups of investigators1accredited to the Committee on Chemotherapeutic and Other Agents of the National Research Council, and the results of the treatment have been collected and summarized by the chairman of the committee, who acted for it and for the Committee on Medical Research. All the penicillin used in this study was provided by Merck & Company, E. R. Squibb & Sons and the Charles F. Pfizer Company. The costs of the penicillin were covered by a contract of the Office of Scientific Research and Development on the recommendation of the Committee on Medical Research. A recent statement of the progress of efforts with respect to penicillin has been published in