Selective culture of human carious dentine for Veillonella strains resulted in the isolation of two strains of a Gram-negative, coccus-shaped bacterium that has not been described previously. Comparative 16S rRNA and dnaK gene sequence analysis indicated that the two strains were homogeneous and comprised a distinct lineage within the genus Veillonella, phylogenetically most closely related to Veillonella rodentium. This was supported by DNA-DNA hybridization, which showed clearly that the two strains were similar and distinct from other Veillonella species, and the production of major cellular fatty acids (C(13 : 0) and C(17 : 1)omega8), which is consistent with other members of the genus Veillonella. Based on these observations, strains RBV81 and RBV106(T) represent a novel species, for which the name Veillonella denticariosi sp. nov. is proposed, with the type strain RBV106(T) (=CIP 109448(T) =CCUG 54362(T) =DSM 19009(T)).