Sulfadiazine is effective in clearing the nasopharynx of meningococci [Neisseria intracellularis meningitidis], since all of 161 meningococcus carriers receiving 8 gms. of the drug over a period of 72 hrs. yielded negative cultures on the 4th day. No untoward effects from the drug were noted and the men so treated reac-quired latent infection but slowly in spite of constant exposure to the specific organism. Some possible practical aspects of these facts are discussed.