Disinfection is the basis of the prevention of infectious diseases of animals - a complex of general organizational and economic and specific antiepizootic measures aimed at the destruction of vegetative and spore forms of pathogens common to humans and animals. The previously widely used classical disinfectants today do not meet the stringent requirements that are imposed on disinfectants. One of such requirements includes a wide range of antimicrobial action of the drug, its toxicological safety, good disinfecting ability regardless of the frequency and duration of use of the drug [6].High adaptation of opportunistic and pathogenic microflora to the active substances of the disinfectant is one of the problems in animal husbandry. One of the sanitary-indicative microorganisms is Escherichia coli, the presence of which in feed, water, on the surfaces of technological equipment and inventory indicates fecal contamination of objects.The purpose of the work is to test a new composite disinfectant "Dezon Vetklin" against E. coli in the production conditions of a breeding plant in the Leningrad region.According to the results of laboratory studies of flushes taken from the treated surfaces of the premises, the composite disinfectant "Dezon Vetklin" in a concentration of 0.2% and an exposure of 12 hours showed an antibacterial effect against Escherichia coli, which indicates a high-quality preventive disinfection of the premises of the dispensary of the maternity ward of the breeding plant.To carry out preventive disinfection of livestock premises, it is recommended to use a modern disinfectant "Dezon Vetklin" in the above concentrations and exposures.