Introduction. Ensuring food security on the territory of the Russian Federation is an urgent issue of modern agro-industrial complex. Production of quality dairy products directly depends on compliance with the rules of cattle hygiene and machine milking technology, violation of which leads to a decrease in milk quality, which is expressed in an increase in the number of undesirable microflora and the number of somatic cells. The purpose of the study was to investigate the embryotoxic and teratogenic effect of a new probiotic preparation on white Wistar rats. Materials and methods. The effect of a new probiotic preparation based on the genus Bacillus on the embryonic and postembryonic development of the fetus at different gestation periods of white Wistar rats is considered. The new probiotic preparation is a biopreparation with antimasatitis effect, developed by FSBEIU VO Kazan GAVM together with “Forterra” Ltd. The experiments were conducted in standard conditions of the vivarium of the Department of Animal Husbandry Technology and Animal Hygiene of the Federal State Budgetary Educational Institution of Higher Education “Kazan State Academy of Veterinary Medicine named after N. E. Bauman”, on clinically healthy white rats, live body weight 190‒220 grams, divided into experimental and control groups according to the principle of analogs. The new probiotic preparation was investigated every day during the whole pregnancy of rats, at a dose of 5000 mg/kg body weight. The research results. It was found that the innovative probiotic preparation based on microorganisms Bacillus subtilis and Bacillus amiloliquefaciens has no embryotoxic and teratogenic effect on the organism of experimental rats and their offspring. Orally administered dose of 5000 mg/kg body weight of a new innovative agent has no toxic effect on the organism of pregnant rats of Wistar line, their embryos and young animals in embryonic and postembryonic periods of development. Conclusion. Based on the obtained data, it can be said that the new probiotic preparation meets the biosafety requirements for the use of drugs used for the prevention of subclinical mastitis in cattle.