Boron is a required trace element for plants, humans, and animals and it has significant influence over biological functions and the immune system. Vaccines have aided humans in the control of many contagious diseases around the world. The success of global immunization campaigns may be possible with the development of effective and low-cost vaccines and adjuvants. For this reason, the present study aimed to determine the adjuvant activity of easily accessible boron compounds. In this study, six different vaccines were prepared, including inactive Staphylococcus aureus bacteria, boric acid, aluminum hydroxide, montanide ISA 50, and ISA 206, ISA 50 + boric acid, and ISA 206 + boric acid combinations. The rate of survival following the challenge, the bacterial load on internal organs, and histopathological findings at the vaccine injection site and in the internal organs were evaluated in vaccinated mice. In addition, the levels of interferon - γ and tumor necrosis factor - α were measured in the vaccinated seropotency groups. The rate of postchallenge mortality was 50% in the control group, and no mortality was encountered in the boric acid group. The boric acid adjuvanted vaccine decreased the bacterial load and postchallenge abscess in the internal organs and also local inflammatory reactions due to montanide adjuvants in combinations. No difference was found in the interferon - γ and tumor necrosis factor - α levels between the control and vaccine groups. It was concluded that boric acid can be used as an adjuvant in inactivated vaccines.