The taxonomic position of two bacterial strains, BN6T and N,N, with the ability to degrade xenobiotic aromatic compounds (naphthalenesulfonates or N,N-dimethylaniline) was investigated. The 165 rRNA gene sequence, the G+C content of the DNA (62-63 mol%) and the detection of ubiquinone Q-10, 2-hydroxymyristic acid and the sphingoglycolipid present clearly placed the two strains into the genus Sphingomonas. Both strains are representatives of one species according to the level of DNA relatedness (70.7%). The strains could be separated from all validly described taxa of the genus Sphingomonas, according to the 16S rRNA gene sequence (the highest sequence similarity observed was 96 % to Sphingomonas yanoikuyae), the pattern of the polar lipids and physiological characteristics. Therefore, the new species Sphingomonas xenophaga is proposed to accommodate strains BN6T (= DSM 6383T) and N,N (= DSM 8566).