Аppearance of a malignant tumor is associated with impaired mechanisms of proliferation, differentiation, apoptosis ability. However, these changes are not enough for immune system to recognize and destroy mutated cells. Weak immunogenicity of tumor-associated antigens (TAA) and the insufficiency of co-stimulating molecules on the surface of tumor cells is a reason for this phenomenon Since biochemical processes of tumor cells and healthy tissue cells are identical, therefore creation of effective chemotherapeutic drugs is limited not by selectivity of their action. So antitumor vaccination is the most effective specific method for both preventing recurrence of a disease and a therapeutic treatment tool in oncology. Xenogeneic proteins are highly immunogenic and effective in breaking immune tolerance to human analogs. In our work, we used sheep testicular AG as a source xenogenic TAAs. Sheep testicles contain a large set of TAAs. Experimental mice were immunized with type liposomal testicular vaccine from sheep, one month after vaccination, to induce tumor growth, cells of carcinoma LLC were implanted in mouse. The life expectancy of the experimental group of mice was 2 times higher compared to the syngenetic control and 20% of them did not develop the tumor at all. In the spleen of mice who did not have tumors after pre-vaccination sheep liposomal testicular AG, T-regulatory cells and T-memory cells were measured. We found a credible decrease in both naive Treg (CD4+CD25+), activated (CD4+CD25+FoxP3+) and both T-memory (CD4+CD44+) and central memory (CD4+CD44+CD62L+) in spleen pre-vaccination mice with compared to the contral intact spleen. Content of IFNg and IL-10 in supernatants of mouse slenocytes derived from vaccinated mice with no tumors was investigated and showed a reliable decrease in the amount of IL-10, but not IFNg. We believe that immunization with xenogenic tumor AGs can lead to the formation of a protective antitumor response.