The present investigation was aimed to analyse the chemical composition of essential oil isolated from Heracleum persicum Desf. ex Fischer and assess its lethal and sub-lethal effects against Tribolium castaneum (Herbst). Essential oil from hydro-distilled seeds of H. persicum was analyzed by gas chromatography-mass spectrometry (GC-MS), and hexyl butyrate (50.58%), octyl acetate (9.80%) and hexyl hexanoate (8.75%) were found as principal constituents. Repellent activity, contact and fumigant toxicity and antifeedant effects of this oil were assessed against the adults of T. castaneum. The essential oil strongly repelled T. castaneum adults even at the lowest concentration (0.035 μL cm -2 ). Complete repellency (100%) occurred when the highest concentration (0.212 μL cm -2 ) was applied for 8 h. T. castaneum was very susceptible to H. persicum oil at both contact and fumigant bioassays. In the fumigant toxicity, essential oil killed the larvae, pupae and adults and significantly decreased larvae emerged from treated eggs. LC 10 to LC 40 values of fumigation adult's bioassay as sub-lethal concentrations were used to evaluate the antifeedant effects. H. persicum essential oil has significant antifeedant effects on T. castaneum adults and decrease of feeding happened when oil concentrations increased. The results of the present study indicate that essential oil of H. persicum, with wide bio-effects on T. castaneum, is a source of biologically active agents which may potentially prove to be efficient insecticides.Additional key words: essential oils; Heracleum persicum; toxicity; repellent; antifeedant.* Corresponding author: asgar.ebadollahi@gmail.com Received: 12-07-14. Accepted: 12-11-14.Abbreviations used: FDI (feeding deterrence index); GC (gas chromatography); LC 50 (lethal concentration required to kill 50% of the population); MS (mass spectrometry); PR (percentage of repellency); RH (relative humidity).