ABSTRACTPasteurellasp. were isolated from tonsillar swabs obtained from 100 dogs and 100 cats; isolation rates were 92 per cent and 99 per cent respectively. Isolates were identified according to recent taxonomic data.P. multocidasubsp.multocidaand subsp.septicawere common in cats but not in dogs.P. caniswas common in both dogs and cats. Compared with strains from dogs, those from cats were more pathogenic for mice. Many of the species isolated are considered potential human pathogens.