The rate of molecular evolution inferred from gyrB gene sequences is faster than that inferred from 16S rRNA gene sequences.gyrB gene sequences have been used in phylogenetic studies of Pseudomonas, Acinetobacter, Mycobacterium, Salmonella, Shigella and Escherichia coli, Aeromonas and the Bacillus anthracis–cereus–thuringiensis group;results from these studies have indicated that gyrB is a suitable phylogenetic marker for the study of phylogenetic and taxonomic relationships at the species level. In the present study, it has been shown that direct sequencing of the gyrB gene could be used for identification and phylogenetic analysis of species of the B. subtilis group.