The constituents of the volatile oil of air-dried aerial parts of Mentha pulegium L. (Lamiaceae) plants wildly growing in Northwest Iran were analysed by GC/MS. 46 components were identified, comprising 96.6% of the essential oil. Monoterpenes (78.9%) were the main class of the identified components followed by a minor proportion of sesqui-
terpenes (11%). Oxygenated monoterpenes (75.3%) were the major subclass of volatile oil components with menthone (38.7%), menthol (11.3%), neomenthol (10.5%), and pulegone (6.8%) as major compounds. Sesquiterpene hydrocarbons (10.6%) were the highlighted subclass of 15 carbons sesquiterpenoidal compounds with (E)-caryophyllene (4.9%) and β-cubebene (2.5%) as their principle representatives. Furthermore, menthyl acetate (C₁₂ acetylated monoterpene derived compound) was contained considerable amounts (5.2%) in the essential oil. In total, volatile oil composition of M. pulegium L. plants studied in the present experiment was characterised as a new menthone type with appreciable amounts of menthol and neomenthol, and it could be used as a potential source of these high value monoterpenes in pharmaceutical and food industries.