A gram-stain-positive, facultatively anaerobic, non-spore-forming, catalase-negative, coccoid-shaped bacterial strain, designated BV2(T), was isolated from the vaginal mucosa of a beef cow in Japan. Phylogenetic analysis showed that the isolate shared high 16S rRNA gene sequence similarity (92.9 %) with Aerococcus suis 1821/02(T) and low similarity (<92.7 %) with any other recognized species of the genus Aerococcus. The DNA G+C content was 44.7 mol%, which is within the range observed among species of the genus Aerococcus (37.5-48.4 mol%). The major cellular fatty acid was C18 : 1ω9c, similar to other type strains of species of the genus Aerococcus. The results of genotypic, phenotypic and chemotaxonomic analyses as well as the low degree of DNA-DNA relatedness with all recognized members of the genus Aerococcus indicate that strain BV2(T) represents a novel species of the genus Aerococcus, for which the name Aerococcus vaginalis sp. nov. is proposed. The type strain is BV2(T) ( = JCM 19163(T) = DSM 27293(T)). Emended descriptions of Aerococcus suis, Aerococcus viridans, Aerococcus urinaeequi, Aerococcus urinaehominis, Aerococcus urinae, Aerococcus christensenii and Aerococcus sanguinicola are also presented.