Abstract The chemical composition of the oils of one population of Satureja montana L. subsp. pisidica (Wettst.) Silic and two populations of S. montana subsp. montana were investigated on the intrapopulational and interpopulational level by GC and GC/MS. All samples of the populations were grouped according to dominant constituents in the oils and chemotype. The results showed a significant individual variability of the oil composition. In all oil samples, the quantity of sesquiterpene compounds was smaller than the quantity of Monoterpene compounds; with the oxygenated monoterpenes being greater than the Monoterpene hydrocarbons. The main constituents of S. montana ssp. pisidica oils were found to be p-cymene (22.4â75.5%), linalool (22.5â68.0%) and carvacrol (26.2â70.5%). The main components of S. montana ssp. montana oils were shown to be p-cymene (14.5â47.7%), trans-sabinene hydrate (14.2â27.1%), linalool (14.4â74.0%), borneol (18.1â29.6%) and p-cymen-8-ol (11.3â27.0%). The domination of the plants of the aromatic chemotype was determined in all of the investigated populations. By comparing the oils of the examined plant populations, it was found that there was more similarity, in quAlltative and quantitative composition of essential oils, the presence of chemo-types and their frequency, than between populations that belonged to the same subspecies and which have habitats similar in basic climatic factors.