abstract the oil-poor hypericum perforatum plants were collected at full flowering from ten wild habitats in lithuania. the essential oils obtained by hydrodistillation were analyzed by gc and gc/ms. the most predominant compound was germacrene d (12.0-29.5%). the second major constituents were -caryophyllene (8.8-10.5%, three oils), caryophyllene oxide (11.9-13.1%, two samples), -eudesma-4(15),5-dien-1-ol (9.1-11.7 %, two oils), -farnesene (9.0%, one sample) and tetradecanal (9.4%) with tetradecanol (9.4%, one oil). the oils were rich in sesquiterpene hydrocarbons (31.8-52.4%). thirty-one out of the eighty identified constituents were found in the all oils. the identified compounds comprised 87.5-95.6% of the oils. key word index: hypericum perforatum hypericaceaeessential oil compositiongermacrene d-caryophyllenecaryophyllene oxide-eudesma-4(15),5-dien-1-ol