in this study, chemical composition and antimicrobial activity of the essential oil of sideritis cypria, which is an endemic taxon in northern cyprus, were investigated. the essential oil obtained by hydrodistillation were analyzed by gas chromatography (gc) and gas chromatography-mass spectrometry (gc-ms). in general, the gc and gc-ms analysis illustrated that fifty compounds were identified representing 96.9% of the oil. major components were epi-cubebol (11.9%), trans-piperitol (8.9%) and pinene (8.1%), respectively. the antimicrobial activity of the essential oil was tested by disc diffusion method against pseudomonas aeruginosa (atcc 27853), escherichia coli (atcc 25922), bacillus cereus (atcc 10876), staphylococcus aureus (atcc 25923) bacteria and candida albicans (atcc 90028) yeast. the results showed that the inhibition zone of s. cypria essential oil against c. albicans at maximum dose (10 l) was higher than positive control nystatin. the oil showed similar inhibitory zone to that of the positive control (tmp-smx) against b. cereus at maximum dosage 10 l. in addition, the inhibitory effect of the oil against e. coli measured only at the 10 l as 10.33 +/- 0.58. furthermore, the inhibition zones against s. aureus was ranged from 9.00 +/- 2.00 to 24.00 +/- 1.73 while p. aeruginosa was found to be resistant in all doses.