A Gram-positive bacterium, strain J18(T), isolated from sludge of a foul water sewer, was subjected to a polyphasic taxonomic study. Phylogenetic analysis of the bacterium based on its 16S rDNA sequence showed that it belongs to the genus Rothia and forms a distinct phyletic clade with the type strain of Rothia nasimurium. Morphological, physiological and chemotaxonomic characteristics supported the assignment of this organism to the genus Rothia and distinguished it from the type strains of all validly described Rothia species. Therefore, it is proposed that this bacterium be classified in the genus Rothia as Rothia amarae sp. nov. The type strain is strain J18(T) (= AS 4.1721(T) = JCM 11375(T)).