The study identified pathogens from clinical and subclinical mastitis in sheep from extensive grazing flocks in south-east Australia. Milk samples were collected from 3,529 Poll Dorset ewes at lamb weaning in Victoria, Australia and a high prevalence of coagulase-negative staphylococci was observed from sheep with subclinical mastitis. Phenotypic characteristics, biochemical tests, nucleotide sequence analysis of 16S rRNA and restriction fragment length polymorphism (RFLP) of gap gene were used to identify Staphylococcus devriesei, a species not previously reported from cases of mastitis in sheep.