The genus Bacillus, commonly referred to as the aerobic spore-bearing bacilli comprise several species that are poorly circumscribed and consequently present considerable difficulties for accurate identification (1-4). Some such as B. cereus are important foodborne pathogens while several species including B.alvei, B. megaterium, B. coagulans, B. laterosporus, B. subtilis, B. sphaericus, B. circulans, B. brevis, B. licheniformis, B. macerans, B. pumilus and B. thuringiensis are emerging as important human pathogens. At present, B. anthracis, the causative agent of anthrax, has been the focus of much attention as a potential agent for bioterrorism. Current methods of identifying species include biochemical tests, serology, long-chain cellular fatty acid analysis and more recently DNA sequence-based methods. However, because of the high degree of sequence homology between some species, a polyphasic approach which includes other rapid methods are being actively pursued. The aim of the present study is to investigate the potential of Matrix Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry (MALDI-TOF-MS) as a rapid and specific method, Bacterial Mass Fingerprinting (Figures 1and 2), for the identification of Bacillus species. Once this is established, the standard operating procedures devised from this study will be used to investigate the potential of this technique for the rapid delineation of B. anthracis isolates.