Bacteriophage is a virus that infects a bacterium by injecting a phage genome into a bacterial cytoplasm and uses a host cell as a propagation mechanism. The studied models of phages show a narrow range of hosts. Previous studies on the investigation of lytic activity of staphylococcal bacteriophages were focused on determining the sensitivity of S. aureus isolated from patients from different clinical material and clinically healthy people. However, there is no information as to how refractory are the already described agents against S. aureus ecovars, isolated from animals. The purpose of the work is to study the lytic activity of the agent “Staphylococcal Bacteriophage” in relation to different biotypes of Staphylococcus aureus. Microbiological treatment of samples for isolation of S. aureus was performed using BD Baird-Parker Agar according to standard techniques. To confirm the presence of S. aureus, tests were used for catalase, coagulase, oxidase, for D-mannitol fermentation, DNase production and acetoin. In cultures belonging to S. aureus, the biotype was determined using the scheme: determining the colour of pigment, the presence of beta hemolysis, the activity of coagulase in the bovine plasma, the formation of colonies in a medium with crystal violet. Determination of the range of action of bacteriophages in relation to clinical isolates of microorganisms was carried out by droplet method. The results of determining the lytic activity of staphylococcal bacteriophage in relation to S. aureus isolates of various biological origin showed that the lytic activity of staphylococcal bacteriophage is most active against S. aureus var. hominis. From the studied cultures S. aureus var. hominis full lysis in the course of dripping were found only in 4.8%, and in 42.8% of cultures showed a semiconfluent lysis. 14.3% of cultures S. aureus var. hominis were subjected to weak lytic activity of the bacteriophage. Also, there were detected 4,8% of cultures of this biotype, which were resistant to staphylococcal bacteriophage. In the study of lytic activity of staphylococcal bacteriophage up to 35 cultures S. aureus var. bovis, the manifestation of the lytic action of only one culture is established. Moreover, the level of lysis was estimated at “+/–”, that is, they showed less than 20 phage colonies. At the same time, the studied by us staphylococcal bacteriophage did not show the lytic action on S. aureus var. avium and S. aureus var. canis. Therefore, conducted studies have shown that the lytic activity of the agent “Staphylococcal Bacteriophage” is directed mainly to S. aureus var. hominis, and practically does not work on other biotypes. In consideration of the apparent lack of activity of phage agents in relation to the studied biotypes, attention should be focused on the specificity of phages, not only within the species of bacteria, but also within their biotypes.