Three Gram-negative, rod-shaped, non-spore-forming bacteria were isolated from clinical specimens between 1992 and 2000. On the basis of 16S rRNA gene sequence similarities, these strains (CCUG 30717T, CCUG 43892 and CCUG 38531T) were shown to belong to the Alphaproteobacteria, most closely related to Ochrobactrum grignonense (99.0 and 98.2 % similarity to the type strain). Chemotaxonomic data (major ubiquinone Q-10; major polyamines spermidine, sym-homospermidine and putrescine; major polar lipids phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidylglycerol and phosphatidylcholine; major fatty acids C18 : 1 ω7c and C19 : 0 cyclo ω8c) supported the affiliation of the isolates to the genus Ochrobactrum. The results of DNA–DNA hybridization and physiological and biochemical tests allowed genotypic and phenotypic differentiation of the isolates from described Ochrobactrum species. Isolates CCUG 30717T and CCUG 43892 were closely related on the basis of DNA–DNA reassociation experiments and therefore represent one novel species, for which the name Ochrobactrum pseudogrignonense sp. nov. is proposed, with the type strain CCUG 30717T (=CIP 109451T). Isolate CCUG 38531T was different from these strains and also from other Ochrobactrum species. For this strain, the name Ochrobactrum haematophilum sp. nov. is proposed, with the type strain CCUG 38531T (=CIP 109452T).