The pathogenicity of the metabolites of B. cereus was determined by bioassays with white mice, chick embryos, rabbits, and kittens. Cell-free filtrates of the cultures of several strains of B. cereus were used for application; in the mice the application was done i. v., i. p. and p. o., in the chick embryos via the allantoic sac, in the kittens p. o. and i. p., in the rabbits via tied-up sections of the small intestine by the loop-test method. It was revealed that some strains of B. cereus produced substances of exotoxin nature under suitable conditions. White mice and chick embryos were the best materials for their detection.