A polyphasic study of strains originally received as Bacillus (now Virgibacillus) pantothenticus, along with strains representing species belonging to Bacillus, Halobacillus and Paenibacillus, was undertaken using amplified rDNA restriction analysis (ARDRA), fatty acid methyl ester (FAME) analysis, SDS-PAGE of whole-cell proteins and routine diagnostic characters comprising 61 biochemical tests in the API system and 15 observations of vegetative cell and sporangial morphology. It revealed the presence within Virgibacillus of an as yet undescribed new species, for which the name Virgibacillus proomii is proposed; V. proomii can be distinguished from V. pantothenticus and members of Bacillus sensu stricto, and from members of Paenibacillus and other aerobic endospore-forming bacteria, by routine phenotypic tests. The type strain of Virgibacillus proomii is LMG 12370T.