In the present study, an assessment of allelopathic effect of Eucalyptus camaldulensis Dehnh. and its various derivatives was assessed on the germination of obligate-root and holo-parasitic weed, nodding broomrape (Orobanche cernua Loefl.). Optimized in vitro O. cernua germination assays were conducted under different experimental setups, to determine the allelopathic potential of sapling, leaf-litter extract, plantation-soil, distilled Eucalyptus oil and purified eucalyptol of E. camaldulensis. A considerable and varying levels of inhibitory allelopathic impact on O. cernua seed germination was observed with all tested materials of E. camaldulensis. These findings indicate the possibility to use of allelopathic potential of E. camaldulensis for managing the underground root parasitic-weed infestation in various agricultural crops.