Background Methicillin Resistant Staphylococcus aureus (MRSA) is a strain of Staphylococcus aureus which is resistant to many antibiotics. Along with the increased incidence of MRSA infections and resistances, WHO has recommended to start looking for other treatment alternatives. Nigella sativa (black seed) has an antibacterial effect. Effects of Nigella sativa on the number of MRSA bacteria in vivo have not been investigated.Aims To prove the effect of Nigella sativa oil and its combination with ceftriaxone toward MRSA count in cultured liver of BALB/c mice.Methods The study design was purely an experimental laboratory with Post Test Only Control Group Design. The samples were 20 males BALB/c mice, randomized into 4 groups. Control was given 0,03 ml aquabidest, P1 was given 0,03 ml ceftriaxone, P2 was given 0,3 ml Nigella sativa oil and P3 was given the combination of 0,03 ml ceftriaxone and 0,3 ml Nigella sativa oil. 0,2 ml (107 cfu/ml) MRSA was injected intraperitoneally at the hour 0. The treatment was given at the hour 16and mice were terminated at the hour 24. Analysis data use Kruskall-Wallis Test and Mann-Whitney Test.Results Results of the mean number of MRSA bacteria in liver culture were K=(83,8 ± 123,65) x 103; P1=(13,96 ± 10,64) x 103; P2=(0,64 ± 1,16) x 103; P3=(0,73 ± 1,28) x 103. The number of MRSA bacteria gave significant results in P2 and P3 toward control group (p=0,016) and P1 (p=0,009). There were no significant difference between control toward P1 (p=0,465) and P2 toward P3 (p=0,597).Conclusion Administration of Nigella sativa oil and its combination with ceftriaxone can reduce the number of MRSA bacteria in liver cultures of BALB/c mice significantly.