Two bacterial strains, G30(T) and A1PC16, isolated respectively from raw milk and raw wastewater, were characterized using a polyphasic approach. Chemotaxonomic characterization supported the inclusion of these strains in the genus Acinetobacter, with Q-8 and Q-9 as the major respiratory quinones, genomic DNA G+C contents within the range observed for this genus (38-47 mol%) and C(16:0), C(18:1)ω9c and C(16:1)ω7c/iso-C(15:0) 2-OH as the predominant fatty acids. The observation of 16S rRNA gene sequence similarity lower than 97% with other Acinetobacter species with validly published names led to the hypothesis that these isolates could represent a novel species. This hypothesis was supported by comparative analysis of partial sequences of the genes rpoB and gyrB, which showed that strains G30(T) and A1PC16 did not cluster with any species with validly published names, forming a distinct lineage. DNA-DNA hybridizations confirmed that the two strains were members of the same species, which could be distinguished from their congeners by several phenotypic characteristics. On the basis of these arguments, it is proposed that strains G30(T) and A1PC16 represent a novel species, for which the name Acinetobacter rudis sp. nov. is proposed. The type strain is strain G30(T) (=LMG 26107(T) =CCUG 57889(T) =DSM 24031(T) =CECT 7818(T)).