Essential oils isolated by steam distillation from the aerial parts of Thymus carnosus Boiss. (before flowering and full flowering stage) were analyzed by capillary GC and GC/MS. Among the 30 compounds identified, the major components were thymol (27.2% and 36.1%), p-cymene (26.2% and 21.3%) and gamma -terpinene (19.6% and 19.1%) before flowering and full flowering stage, respectively.