Two methylamine- and N,N-dimethylformamide-utilizing Paracoccus spp. are described. These bacteria are gram-negative, nonsporeforming, nonmotile, coccoid or short rod-shaped organisms. Their DNA base composition is 62 to 68 mol% G + C. Their cellular fatty acids include large amounts of C18:1 acid. Their major hydroxy acids are 3-OH C10:0 and 3-OH C14:0 acids. The major ubiquinone is Q-10. These bacteria are distinguished from Paracoccus denitrificans and Paracoccus alcaliphilus by physiological characteristics and by DNA-DNA-homology. Paracoccus aminophilus sp. nov. and Paracoccus aminovorans sp. nov. are proposed. The type strain of P. aminophilus is DM-15 (= JCM 7686), and the type strain of P. aminovorans is DM-82 (= JCM 7685). Paracoccus halodenitrificans is distinguished from other Paracoccus species on the basis of cellular fatty acid composition, hydroxy fatty acid composition, and DNA-DNA homology. It may not be a valid member of the genus Paracoccus.