The taxonomic position of three Lactobacillus-like micro-organisms (strains SG293(T), SG296 and SG310) isolated from fermented rice grain (Oryza sativa L. subsp. japonica) in Japan was investigated. These heterofermentative lactic acid bacteria were Gram-stain-positive, rod-shaped, facultatively anaerobic, non-motile, non-spore-forming and did not show catalase activity. 16S rRNA gene sequence analysis of strain SG293(T) revealed that the type strains of Lactobacillus malefermentans (98.3 %), Lactobacillus odoratitofui (96.2 %), Lactobacillus similis (96.1 %), Lactobacillus kimchicus (96.1 %), Lactobacillus paracollinoides (95.9 %) and Lactobacillus collinoides (95.7 %) were the closest neighbours. Additional phylogenetic analysis on the basis of pheS and rpoA gene sequences, as well as biochemical and physiological characteristics, indicated that these three strains were members of the genus Lactobacillus and that the novel isolates had a unique taxonomic position. The predominant cellular fatty acids were C18 : 1ω9c and C19 : 1 cyclo 9,10. Because low DNA-DNA hybridization values among the isolates and Lactobacillus malefermentans JCM 12497(T) were observed, it is proposed that these unidentified isolates be classified as a novel species of the genus Lactobacillus, Lactobacillus oryzae sp. nov. The type strain is SG293(T) (= JCM 18671(T) = DSM 26518(T)).