Abstract The essential oils from two Compositae species of Iran: Centaurea depressa M.B and Carduus pycnocephalus L. obtained by hydrodistillation were analyzed by GC and GC/MS. Piperitone (35.2%) and elemol (14.1%) were the main components among the 26 constituents characterized in the oil of C. depressa representing 90.5% of the total components detected. Twenty-nine components were identifed in the oil of C. pycnocephalus representing 83.4% of the total oil with hexadecanoic acid (23.3%) as main constituent.