Abstract The essential oils obtained by hydrodistillation from the flowers, leaves, stems and roots of Hypericum perforatum L. growing wild in the Northeast of Iran were investigated by GC and GC-MS. The major constituents of the flower and leaf oils appeared to be α-pinene (36.0 % and 14.5 %), β-selinene (10.1 % and 25.4 %) and α-selinene (10.0 % and 13.5 %), respectively. The other main component in the flower oil of the plant was β-pinene (15.5 %). Germacrene D (37.8 % and 22.2 %) was the predominant compound in the stem and root oils, respectively.