A bacterial strain isolated from human faeces, M-165T, was characterized in terms of its phenotypic and biochemical features, cellular fatty acid profile, menaquinone profile and phylogenetic position (based on 16S rRNA gene sequence analysis). A 16S rRNA gene sequence analysis showed that the isolate was a member of the genus Parabacteroides. Strain M-165T was closely related to Parabacteroides merdae strains, showing 98 % sequence similarity. The strain was obligately anaerobic, non-pigmented, non-spore-forming, non-motile, Gram-negative, rod-shaped and was able to grow on media containing 20 % bile. Although the phenotypic characteristics of the strain M-165T were similar to those of P. merdae, the isolate could be differentiated from P. merdae by means of API 20A tests for L-arabinose and L-rhamnose fermentation. DNA-DNA hybridization experiments revealed the genomic distinctiveness of the novel strain with respect to P. merdae JCM 9497T (<or=60 % DNA-DNA relatedness). The DNA G+C content of the strain is 47.6 mol%. On the basis of these data, strain M-165T represents a novel species of the genus Parabacteroides, for which the name Parabacteroides johnsonii sp. nov. is proposed. The type strain is M-165T (=JCM 13406T=DSM 18315T).