hydrodistilled volatile oils from the aerial parts of ducrosia anethifolia and ducrosia flabellifolia were investigated by gas chromatography (gc) and gc/mass spectrometry (gc/ms). the plants were collected from west and southwest iran. thirty-two compounds in d. anethifolia and thirty-three compounds in d. flabellifolia were identified, representing 93.4% and 88.2% of the total oils, respectively. the major components of d. anethifolia oil were dodecanal (28.8%), decanal (21.1%), (2e)-tridecen-1-al (15.8%) and (2e)-dodecenal (13.4%). the most abundant components in essential oil of d. flabellifolia were decanal (32.8%), dodecanal (32.6%), decanol (4.3%) and (2e)-tridecen-1-al (3.3%). cytotoxic activity assessed on three human cancer cell lines (k562, ls180 and mcf-7) showed that essential oil from d. anethifolia represented good to moderate cytotoxic activity, while d. flabellifolia had a moderate to weak activity.