Abstract The bark oils of Goniothalamus macrophyllus Hook. f., obtained from two different sites, were investigated by capillary GC and GC/MS. The oils were found to possess little differences in the chemical composition but considerable variation in the levels of the individual components. The oils were rich in monoterpenoids (91.8â94.0%), with terpinen-4-ol at 38.8% and 42.7%, respectively, as the dominant component. The major differences between the oils were the presence of appreciable amounts of 1,8-cineole (18.1%), geranyl acetate (11.1%) and geraniol (9.7%) in one sample and relatively low amounts of these compounds in the other sample. However, the latter sample contained signifi cantly higher concentrations of (Z)-Î²-ocimene (25.4%) and Î±-terpineol (10.0%).