Background: Staphylococcus aureus, is one of the most pathogens of the respiratory and intestinal tract, and it is widely spread in hospitals, especially resistant ones. Surprisingly, thyme oil is effective against both sensitive and resistant bacteria. Aim: The study aims to find treatments of plant sources to reduce toxic effects and side effects of chemical pharmaceuticals used in therapeutic purposes. Methods: The study was carried out on the thyme oil extract that was bought from local markets and classified by the Herbarium of the University of Baghdad, the oil was extracted at Ibn Al-Betar Research Center. Tube Dilution Method was used to determine the minimum inhibitory concentration(MIC) toward staphylococcus aureus.  Results the first detection of the functional groups in oil extract of thyme showed that it contains phenols, flavonoids, tannins. Interestingly, phenols are considered basic antioxidant material, that is what gives the bactericide effect to thyme oil. The difference in the (MIC) of thyme oil against both bacteria was twice as the (MIC) of sensitive bacteria was at a concentration of 12% and an inhibitory diameter of (15mm) compared to gentamicin (12mm), while the (MIC) of thyme oil against the resistant bacteria was at a concentration of 25% with an inhibitory diameter of (20mm) compared to gentamicin (15mm). In both cases, the results showed that the inhibitory effect of thyme oil exceeds that of the standard antibiotic. Conclusion:The thyme oil in different concentrations proved its effectiveness on sensitive or resistant Staphylococcus aureus compared to the standard antibiotic.