The chemical composition of the essential oil of Micromeria cilicica (Labiatae) that has been used in folk medicine were analysed by GC, GC-MS, H-1 NMR and C-13 NMR. The totals of 34 components in hydrodistillation, 30 components in steam distillation were detected. The major component characterized in the essential oils was pulegone (66.55, 64.10%) and other main components were determined as cis-p-menthone (21.71, 25.31%), trans-p-menthone (9.59, 5.59%), nerol (0.35, 2.49%) and 3-octonol (0.81, 0.25%), respectively. Essential oils obtained by hydro and steam distillation and organic solvent extracts of the aerial parts of the plant were investigated for antimicrobial activities on several microorganisms including bacteria and yeast. Moreover, the main constituent of the oil has been tested against the same microorganisms. The extracts and pulegone exhibited a significant antibacterial and antifungal activity. The activities were increased depend on the amount of extracts and pulegone. Pulegone also showed antimicrobial activity, particularly against Candida albicans and Salmonella typhimurium. Furthermore Candida albicans is the most susceptible to pulegone giving two times the effect of nystatin. (C) 2004 Elsevier Ireland Ltd. All rights reserved.