the chemical composition of leaf essential oil of vepris unifoliolata was characterized by hydrocarbon monoterpenes, -pinene (60.5%), myrcene (6.8%), limonene (5.1%), (e)--ocimene (4.9%) and -phellandrene (4.7%). the chemical composition of bark essential oil of v. unifoliolata was original and characterized by a high content in heat-sensitive compounds isofuranodiene (43.9%) and germacrone (17.1%). these compounds bearing the (e,e)-1,5-cyclodecadiene structure were known to rearrange and degrade during the gc-fid and gc-ms. the true content of isofuranodiene/curzerene, germacrone/trans--elemenone, germacrene a/-elemene and germacrene b/-elemene was evaluated by combination of 13c-nmr data (intensities of signals of selected carbons) and gc-fid. thus, a correct quantitative analysis of bark oil of v. unifoliolata was provided.