Abstract: The essential oil of Micromeria biflora ssp. arabica K. Walth was obtained by hydrodistillation and analyzed by GC/MS. Out of 39 peaks (representing 99.0% of the oil); 30 components were identified, representing 98.2% of the total oil. The major constituents were trans-caryophyllene (43.7%), caryophyllene-oxide (18.0%), spathulenol (8.5%), α-humulene (4.6%), α-myrcene (3.1%) and germacrene-D (3.1%). The antimicrobial activity of the oil was also evaluated.