Management of stored-grain insects using gamma radiation could be enhanced by other feasible control methods such as essential oils as potential alternatives to chemical insecticides. This work was carried out to find the effect of two essential oils rosemary) Rosmarinus officinalis L.(and cinnamon(Cinnamomum aromaticum(  and /or gamma radiation doses separately on Tribolium castaneum adult's mortality and the combined effect of gamma radiation doses and at LC₅₀of  each essential oil (based on Probit analysis) on adult's mortality. The insects were subjected to five radiation doses (150, 200, 250, 300 and 350 GY), then exposed to the LC₅₀'s from each essential oil and its effect on certain biological aspects of T. castaneum. The mortality rate was increased in the combined treatments of (LD₅₀of gamma radiation and LC₅₀of the two essential oils) more than any of the separate treatments. The additive effect was more detectable when higher doses of gamma radiation were combined with LC₅₀ of either of the two essential oils. From the mentioned results, the mortality effect of the essential oils against stored grain pests can be enhanced by its combining with gamma radiation. As well, the results showed that the combination experiments caused significant reduction in the number of eggs deposited per female, hatchability percentage of eggs, total larval duration, the pupal period and total developmental period, while the pre-oviposition period and incubation period of eggs were obviously increased. From the mentioned results, the insecticidal effectiveness of the essential oils against stored grain pests can be enhanced by combining the oil treatments with gamma radiation.