1. There is recorded for the first time an outbreak of milk-borne bacillary dysentery which has been proved to be due toB. dysenteriaeSonne.2. In this milk-borne outbreak of Sonne dysentery there were over 150 cases and no deaths, the absence of mortality being in marked contrast to the high mortality rate which accompanies milk-borne outbreaks of Flexner dysentery.3. Several milk-borne outbreaks of enteritis simulating dysenteric infections have been recorded in which the evidence has pointed to a living bacillus of unrecognised type as the causal agent. It is obvious that in futureB. dysenteriaeSonne will require to be excluded from the group of the unrecognised viruses.