abstract the chemical composition of the volatile oils of seeds of foeniculum vulgare miller from two spanish locations (santander and aranjuez) were investigated by means of gc and gc/ms. leaf and stem oils of f.vulgare from aranjuez were also examined. two different chemotypes have been found in the seeds: (i) methyl chavicol (54.9%), fenchone (24.6%) in the seeds collected in santander; and (ii) (e)-anethole (54.9-38.1%), fenchone (22.2-34.4%) in the seeds gathered in aranjuez. the oil from the leaves collected in aranjuez (april, june) was found to contain methyl chavicol (12.3-12.1%), -phellandrene (9.4-27.2%), limonene (25.3-18%) and fenchone (19.4-18.3%) as major constituents. the oil from the stems gathered in aranjuez (september) was characterized by a high content of (e)-anethole (17.4-3-3%), -pinene (9.7-14.4%), -phellandrene (24.3-31.4%), p-cymene (11.5-5-2%), limonene (11.6-15%) and fenchone (9-1-17-5%).