abstract the chemical composition of the essential oils of thymus serpyllum l. ssp. serpyllum var. serpyllum growing wild in vilnius (east lithuania) has been studied. the samples collected at full flowering were analyzed by gc and gc/ms. thirty-six identified constituents made up 86.5-94.9% of the oils. the main constituents were 1,8-cineole (8.9- 13.9%), caryophyllene oxide (6.5-12.5%), borneol (7.4-10.5%), -caryophyllene (8.5-10.2%), germacrene d (5.8-13.5%), camphor (5.2-7.4%), camphene (4.2-8.2%) and myrcene (4.1-8.8%). the oil containing approximately equal amounts of the first two major constituents was attributed to 1,8-cineole/caryophyllene oxide-chemotype. the most stable characteristic of the oils under study was the quantity of compounds with bornane carbon skeleton (16.7-18.5%, camphor + borneol + bornyl acetate).