The humoral and cellular immune response in guinea pigs vaccinated with Rev-1 vaccine and simultaneously treated with antibiotics (oxytetracycline, streptomycin or enrofloxacin) or 4 weeks post-vaccination were evaluated in the present study. Groups vaccinated and simultaneously treated with oxytetracycline or 4 weeks post-vaccination showed delayed or abrupt reduction respectively in antibody production, lymphocyte transformation, phagocytic percent and intra-cellular killing one week post administration of this antibiotic while groups vaccinated and simultaneously treated with streptomycin or 4 weeks post-vaccination showed abrupt reduction in antibody titer and moderate reduction in phagocytic percent, intra-cellular killing and lymphocyte transformation. Treatment by enrofloxacin simultaneously with Brucella melitensis Rev-1 vaccine or at peak of vaccination (4 weeks post-vaccination) cause non-significant variation in both humoral and cellular immune response. Therefore oxytetracycline and streptomycin should not be recommended for animal treatment during exposure to Brucella melitensis Rev-1 vaccine. In contrast enrofloxacin exhibited a satisfactory margin of safety upon the humoral and cellular immune responses to Brucella melitensis Rev-1 vaccine.