RESUMEN
The resistance developed by bacteria against antibiotics is an urgent problem in the medical field, therefore, the researchers always work to find new antibiotics and develop them. And because of what was known of the ancient use of plants which contain essential oils as antiseptics, researches have tended to study this effect accurately. The aim of the research is to study the antibacterial activities of Mentha microphylla on several types of bacteria. The essential oil was extracted from dry and fresh samples of the studied plant by water distillation method. The disk diffusion method was used to study the effect of the essential oil on the bacterial groups which were as follows: Staphylococcus aurous, bacillus subtiis, Micrococcus luteus, Escherichia coli and Pseudomonas aeruginosa, and then calculate the MIC values. The bacterial effect in fresh plant case was as follows: Bacillus subtilis [IZ=18.33 mm, MIC=0.4 mg/ml], Staphylococcus aureus [IZ=14 mm, MIC=0.4 mg/ml], Escherichia coli [IZ=l3mm, MIC=12.6 mg/ml], Micrococcus luteus [IZ=11.33 mm, MIC=12.6 mg/ml] and Pseudomonas aeruginosa [no effect]. While in case of dry plant the effect was as follows: Bacillus subtilis [IZ=16.33 mm, MIC=0.8 mg/ml], Staphylococcus aureus [IZ=9.67 mm, MIC=0.8 mg/ml], Escherichia. Coli [IZ=7.6 mm], Micrococcus luteus [IZ=10.33 mm, MIC=12.6 mg/mi] and Pseudomonas aeruginosa [no effect]