A total of 113 Bordetella bronchiseptica strains, isolated from 11 different host species worldwide, were characterized by ribotyping with restriction enzyme PvuII. Sixteen distinct ribotypes were identified, and each ribotype contained five to seven restriction fragments ranging in size from 1.8 to 5.6 kb. Approximately 88% of the swine isoaltes were identified as ribotype 3 strains. Isolates from dogs also displayed little variation; 74.1% were found to be ribotype 4 strains. Strains obtained from the remaining nine host species belonged to 15 different ribotypes. There was no association between geographic location and ribotype. The technique which we used may be useful for epidemiologic studies in which the transmission of B. bronchiseptica, both within and between species, is investigated.