Summary.The ability of 111 isolates of 33 species ofBacillusto hydrolyze hippurate into benzoic acid and glycine was tested. All, other than the strains classified asB. badius, B. cereusvar.mycoides, B. cereusvar.thuringiensis, B. macquariensis, B. medusa, B. pacificus, B. psychrosaccharolyticusand someB. maceransandB. polymyxastrains, were positive by thin layer chromatography (TLC). Of the 4 methods compared (hippurate agar, the sulphuric acid method, precipitation with ferric chloride and TLC), only the TLC procedure allowed a rapid and definite detection of the hydrolytic product, benzoic acid. The use of hippurate hydrolase as an additional diagnostic aid in the differentiation of aerobic spore‐forming bacilli is discussed. Other characters were used to compare some recently describedBacillusspp. The combinationB. cereussubsp.medusan. subsp. is propose