This study was designed to examine the in vitro antimicrobial and antioxidant activity of the essential oil and various extracts prepared by using solvents of varying polarity from Cyclotrichium origanifolium (Labill.) Manden. & Scheng. The essential oil was particularly found to possess stronger antimicrobial activity while other non-polar extracts and subtractions showed moderate activity and polar extracts remained almost inactive. GC and GC/MS analysis of the oil resulted in the identification of 26 compounds, representing 99.6% of the oil; pulegone (49.8%), menthone (32.5%) and limonene (6.0%) were the main components. The samples were also subjected to a screening for their possible antioxidant activity by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and P-carotene-linoleic acid assays. In the first case, the free radical scavenging activity of polar subfraction of deodorized methanol extract (DeMW) was superior to all other extracts. Especially polar extracts exhibited strongest activity than the non-polar extracts. In the case of linoleic acid system, oxidation of linoleic acid was effectively inhibited by non-polar (chloroformic) subfraction methanol extract (MC), where the oil was less effective. MC extract exhibits 79.2% inhibition that is close to synthetic antioxidant reagent BHT when compared to the other extracts tested. (c) 2004 Elsevier Ltd. All rights reserved.