A small gram-negative motile bacillus was isolated from laboratory poults affected by acute respiratory disease (rhinotracheitis) of turkeys. The bacterium was inoculated intranasally into susceptible day-old poults; the poults developed typical clinical signs of acute respiratory disease, and the bacterium was reisolated. This same bacterium was isolated from commercial poults with typical signs of acute respiratory disease but not from poults of similar age which were clinically normal. The bacterium has not been identified taxonomically. We conclude that it is a primary etiologic agent for acute respiratory disease of turkey poults.