Abstract The essential oil of the artificial hybrid Hypericum âHidcoteâ, one of the most cultivated St. John's worts in European and American gardens, was analyzed for the frist time by GC and GC/MS. Forty-six components were identified, representing 91.5% of the oil. The sesquiterpene fraction gave the highest contribution (68.4%), whilst monoterpenes amounted to 22.5%. The major constituents were β-pinene (11.9%), α-humulene (7.4%), β-caryophyllene (6.5%) and α-selinene (5.4%). Results confirm that hybridization may generate novel secondary chemistry in plants. Key Word Index: Hypericum âHidcoteâGuttiferaeessential oil compositionβ-pinene