Violation of production and storage regimes can cause contamination of milk and dairy products with spore microorganisms that produce toxins and cause foodborne illness. Of particular importance among such microorganisms is Bacillus cereus, which is the etiological agent of various types of food poisoning. In various types of food products, the joint vegetation of B. cereus with other opportunistic and pathogenic microorganisms is quite often recorded. The features of cultivation of potentially toxigenic strains of B. cereus isolated from milk and dairy products were studied, the tendencies and patterns of their joint vegetation with other microbial contaminants (S. aureus, Proteus spp. and E. coli), which increase the risk of toxic infections of mixed etiology, were determined. It has been established that with the simultaneous cultivation of S. aureus and B. cereus, a certain mutual synergistic effect is observed, accompanied by activation of the process of toxin formation by enterotoxigenic strains of S. aureus. A synergistic effect was observed both in the cultivation medium and in model products. The degree of this mutual influence is largely determined by the cultivation conditions, the composition of nutrient media, and the ratio of the initial levels of contaminants.