Brucella melitensis infection remains a serious health threat to humans and livestock in poorer countries in the Middle East. Vaccination with the isolated crude protein protects against B. melitensis infection. In this study, the efficacy of protective and immunogenicity of a crude protein extract of B. melitensis is administered and evaluated in rats. The immunogenicity of crude protein in the animal blood was assessed by SDS-PAGE and Western blot. The results show that certain proteins were found to be more immunogenic; their molecular weights were (21, 23, 24, 25, 28,31, 34.45, 54.66,83 and 157 kDa). ELISA kits were used to measure the concentrations of IL-4 and IFN- in serum. In contrast to IFN-γ, this study found that the group receiving extracted protein had considerably higher serum levels of IL-4 compared to the control healthy and REV1 group.