Background The economic downturn experienced by farmers and the fear of milk borne infection are of a greater public health concern. Haptoglobin, Serum Amyloid A, IL-12 and IL-10 in lactating Friesian cows vaccinated with prototype killed S. aureus mastitis vaccine and challenged with S. aureus were evaluated. Bacterin concentration at 10 8 cfu /ml of the local isolate of S. aureus was adjuvanted with KAl(SO₄)₂. Six lactating Friesian cows were grouped into A= Negative control, B = Positive control and C = vaccine group. Group C was vaccinated intramuscularly with 2ml of the monovalent vaccine, groups A and B with physiologic normal saline. Groups B and C were later challenged with the live bacterium via intramammary route . Result There was a significant increase in IL-10 concentration in vaccinated group post primary vaccination (PPV), booster phase (PB) and during the bacterial challenge phase. There was also a significantly increased IL-12 concentration in the vaccinated group at 24 hours, weeks 1 and 2 PPV. Haptoglobin at 12 and 24 hours PPV had a significant difference in group C. During the PB at 8 and 12 hours there was a significant difference in group C. During the bacterial challenged phase at 0, 3, 24 hours and day 7 PC there was a significant difference in group B. At 8 hours PC there was a significant difference in group C. For Serum Amyloid A, during PPV at 0, 3, 8, 12, 24 hours and weeks 1 and 2, the concentrations was significantly different in groups C. During PB at 0, 3, 8 and 12 hours PB there was a significant difference in groups C. During the bacterial challenge phase at 3, 8, 12, 24 hours, days 7 and 14 PC there was a significant difference in group B. At 0 hour PC there was a significant increase observed in group C. Conclusion The developed prototype killed S. aureus mastitis vaccine using local isolates was able to stimulate acute phase proteins and pro-inflammatory cytokines. The pattern of responses PC indicated protection, thereby suggesting that vaccination can protect against mastitis infection in dairy cows.