Roots, stems, pedicels, flower and dry leaves and fruits of giant-hogweed (Heracleum mantegazzianum) were steam-distd. to recover volatile oils. The spent fruits were addnl hexane-extd. for 3 weeks to isolate angelicine and 5,6-dimethoxyangelicine. The oils were analyzed for chem. comp. by chromatog. and mass spectrometry. p-Cymene was the main component of roots, pedicels and stems-derived oils (42.81%, 58.42% and 49.94%, resp.), beta-guaiene of leaves-derived oil (35.43%) and Me(CH2)(7)OC of the flowers and fruits-derived oils (68.03% and 59.10%, resp.). The lowest yield of the oil was obsd. at processing stems (450 mg/100 g) and the highest for fruits (950 mg/100 g).