The rust flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), is the most prevalent pest in stored food for human and animal consumption.The current study was conducted to determine the efficacy of microwave energy and gamma radiation on T. castaneum larvae, pupae, and adults. Microwave was applied with exposure times of 30, 60, 120, 180, 240, and 300 sec. at the powers of 180, 300, and 450 W. In addition, gamma radiation was applied at a dosage of 200, 400, 600, 800, and 1000 Gray. Mortality percentage was recorded after 1, 2, 3, 4, 7, and 10 days, and LD₅₀ was recorded after 7 days of treatment. The results indicated that mortality of T. castaneum increased with increasing doses and exposure time. The mortality of T. castaneumincreased, reaching 100% at power levels of 300 s and 450 W. The LT₅₀ and LT₉₀ decreased as power levels and exposure time increased. Moreover, the dosage of 1000 Gy caused 85.0 and 65.0% mortality after 7 days of irradiation for larvae and adult stages. The required dosage of gamma radiation to kill 50% (LD₅₀) of adults after 7 days was 580.1 Gy. Therefore, the use of microwave energy and gamma radiation is a very important alternative method to protect stored grains and their products against T. castaneum.