Objective: Kundmannia sicula is an herbaceous plant belonging to the family Apiaceae and is distributed in the Mediterranean coastal areas where it occurs in arid places. In this work, we have analysed the essential oil distilled from the aerial parts of K. sicula from Sicily (Italy) and its biological activity. Methods: GC-MS was used to analyze the chemical composition, whereas its antioxidant capacity and cytotoxicity on three human tumour cells (A375, MDA MB-231 and HCT 116) were evaluated by DPPH, ABTS, FRAP and MTT methods, respectively. Result: The essential oil resulted very rich of the sesquiterpene hydrocarbon germacrene D (81.2%). Moreover, the K. sicula oil displayed relevant scavenging activity towards the ABTS radical (IC50 values of 14.5 Î¼g/ml) and noteworthy antiproliferative effects on tumour cell lines (IC50 values in the range 21.59â31.94 Î¼g/ml). Conclusion: Results of this study may support uses of K. sicula as a natural source of germacrene D to be exploited on an industrial level.