The essential oils of water distilled aerial parts of Thymus haussknechtii and Thymus kotschyanus var. kotschyanus (Lamiaceae) were analysed by GC/MS system. Seventy-eight components were identified comprising 88.0 and 91.3% of the total components in the oils, respectively. 1,8-Cineole (21.5%) was the dominant compound in Thymus haussknechtii oil and thymol (47.5%) was the main component in the oil of Thymus kotschyanus var. kotschyanus. Copyright (c) 2004 John Wiley & Sons, Ltd.