The in vitro antimicrobial and antioxidant activities of the essential oil and methanolic extract of Micromeria fruticosa ssp serpyllifolia as well as the composition of the essential oil were examined. The essential oil exhibited activity against 14 bacteria, three fungi and a yeast, with minimal inhibitory concentration (MIC) values ranging from 31.25 to 125 mul ml(-1) whilst the methanolic extract was inactive. Antioxidant activity was measured by two methods, namely scavenging of the free radical DPPH and inhibition of linoleic acid oxidation. The methanolic extract exhibited significant antioxidant activity in both assays, providing 50% inhibition at 70.9 +/- 0.5 mug ml(-1) concentration in the DPPH assay and inhibiting linoleic acid oxidation to 59% at 2mg ml(-1) concentration, whilst the essential oil showed activity only at higher concentrations. The gallic acid equivalent total phenolic content of the methanolic extract was found to be 55.2 +/- 2.00 mug mg(-1) dry weight extract (5.5% w/w). The chemical composition of the hydrodistilled essential oil was analysed by means of GC/MS. Twenty-nine constituents were identified, the main ones being piperitenone (50.61%) and pulegone (29.19%). (C) 2004 Society of Chemical Industry.