Technical Abstract: Two species of Bordetella, B. avium and B. hinzii, are known to infect avian hosts. B. avium is the etiologic agent of turkey coryza, a disease of high morbidity. B. hinzii, though commonly acquired from the respiratory tracts of diseased poultry, has not been demonstrated to be pathogenic in either chickens or turkeys. However, no systematic evaluation using genetically distinct strains has been reported. This study evaluated the virulence in turkeys of 6 unique B. hinzii strains with different genetic backgrounds and obtained from a variety of hosts. Three outcomes were observed: 1) tracheal colonization with induction of mild to moderate respiratory disease (2 strains), 2) tracheal colonization in the absence of disease (3 strains), and 3) absence of both tracheal colonization and disease (1 strain). Colonization of some poults resulted in significant tracheal lesions, as determined by histopathological examination, although there was not an absolute correlation between clinical signs and the presence of tracheal lesions. Strains able to colonize turkeys induced B. hinzii-specific antibody responses, as measured by ELISA, in only a subset of birds. One strain representative of each of the 3 categories above was also used to infect chicks. None were able to colonize the trachea and no clinical signs were observed in any chick. These results suggest that some strains of B. hinzii may be virulent in poults and that this agent may be of concern to turkey producers.