Mastitis poses a major economic and health problem in herds of dairy cows. The many years of taking different approaches to treating mastitis have not resulted in an adequate solution, so that the problem of mastitis is still present and acute. The treatment of mastitis using antibiotics yields satisfactory results, but it implies substantial costs for treatment and losses in rejecting milk. Due to the above reasons, a new area of scientific research offers possibilities for finding new solutions to the ever present problem of mastitis - immunoprophylaxis. Vaccines against mastitis available at this time are still not sufficiently effective in general practice, and they are at the level of experimental vaccines. All barn vaccines which have been worked on so far have been significantly experimentally successful. The success is in a significant increase in the antibody titer in serum (but not in milk), as well as in reducing the incidence of clinical and subclinical mastitis cases among experimental and control animals. Nevertheless, it is still believed that immunoprophylaxis, as a method for preventing inflammation of the udder and the occurrence of mastitis, is still an insufficiently investigated field of scientific research. Many scientists are engaged on the problem of finding a vaccine against mastitis, but the coplexity of the mammary gland and the specific permeability of the blood-milk barrier do not permit these efforts to be as successful as they might be if this were not the case.