Four strains of a hitherto unrecognized Gram-positive, catalase-negative, facultatively anaerobic, rod-shaped bacterium isolated from human sources were characterized using phenotypic and molecular taxonomic methods. Comparative 16S rRNA gene sequencing demonstrated that the bacterium represents a new subline within the Lactobacillus casei/Pediococcus rRNA group of the genus Lactobacillus. The unknown bacterium was readily distinguished from all other described Lactobacillus species and related taxa by biochemical tests and electrophoretic analysis of whole-cell proteins. On the basis of phylogenetic and phenotypic evidence, it is proposed that the unknown bacterium be classified as Lactobacillus coleohominis sp. nov. The type strain of Lactobacillus coleohominis is CCUG 44007(T) (= CIP 106820(T)).