Of 103 cases of bacillary dysentery, 80% became convalescent carriers. The av. duration was 34 days, but it was more prolonged in Flexner than in Sonne or "Newcastle" infections. Passive carriers were identified, by cultural surveys. A total of 6,324 cultures were performed on individuals free of diarrhea for the preceding yr. and 3.8% were passive carriers of S. dysenteriae. The prevalence varied slightly by age but markedly by locality. The carrier state rarely continued up to or beyond 1 yr. Carriers tend to be concentrated about cases and may be found by testing cases, recovered cases and household and other intimate contacts.