Abstract The GC, GC/MS analysis revealed more than 80 individual components in the volatile fractions of St. John's Wort (Hypericum perforatum L.) grown in Greece, from which 69 have been identifed. Germacrene D was the main component found in the hydrodistilled oils from wild-grown (22.8%) and cultivated plants (16.9%), respectively, followed by 2-methyloctane (10.8â17.8%), Î²-caryophyllene (6.6â10.3%), Î±-pinene (5.2â10.1%) and bicyclogermacrene (4.1â4.8%). Fourteen of the constituents characterized in the oils of wild-grown plants were not detected in the oils of cultivated plants.