Introduction. Currently, there is a wide implementation of probiotics for therapeutic use for the treatment and recovery of health. Based on this, numerous studies are conducted in order to identify possible risks, features, and confirm the beneficial effects of various strains of microorganisms on the body. Probiotics based on Bacillus subtilis, represented by a complex of spore-forming bacteria, are antagonists of pathogenic and opportunistic microorganisms, they also contribute to the restoration of populations of lacto- and bifidobacteria, reduce the population of opportunistic bacteria, (E. coli for example) and other microorganisms, that make up the normoflora of the gastrointestinal tract (GI tract), for ensuring its normal functioning. The purpose of the study was to determine the sensitivity of probiotic drugs based on the B. subtilis strain to antibacterial drugs to assess the possibilities of joint use or complex therapy. Materials and methods. Considering probiotic strains in the drugs Probiotic no. 1 and Probiotic no. 2, special attention was paid to their sensitivity to antibiotics. To determine the antibiotic resistance of beneficial strains of bacteria of the genus Bacillus, which are part of probiotics, the disc diffusion method (DDM) for determining antibiotic resistance using standard discs was used. In this study, the antibiotic resistance of probiotics based on B. subtilis strains to a certain range of antibiotics was revealed. Research results, discussion. The results obtained show that Probiotic no. 1 can be used in conjunction with the antibiotics benzylpenicillin, oxacillin and spiramycin. Probiotic no. 2 is resistant to amoxicillin, which means it can be successfully used for joint therapy with the antibiotic. Complex therapy is possible with benzylpenicillin, furazolidone and oxacillin under certain conditions (depending on the concentration of the antibiotic), since the result is moderately sensitive. Conclusion. The resistance of probiotic strains to antibacterial drugs significantly increases the effectiveness of their joint use and interaction in complex therapy to maintain microbiological balance and gastrointestinal health.