Abstract Microwave-assisted hydrodistillation (MWHD) and hydrodistillation (HD) were carried out for the analysis of volatile components in whole and ground fruits of Foeniculum vulgare Miller (fennel). Fruits were distilled using a microwave oven modified to fit a Clevenger-type apparatus. The effect of microwave energy on the yield and composition of the essential oil was investigated against the classical hydrodistillation. All the essential oils were analyzed by GC-FID and GC/MS. (E)-anethole was found as the main compound in the oils of both whole and ground materials (82.2â86.8%) using the two methods. Methyl chavicol (4.0â4.9%) and limonene (2.2â4.9%) were also found in fennel oils obtained by HD and MWHD. The amounts of identified components in the oils obtained from whole and ground fennel fruits were not affected significantly by microwave energy except for limonene.