Background: radiation protection concepts and philosophy have been evolving over the past several decades. The inadvertent exposure of  human from various source of radiation causes ionization of  molecules, setting off potentially damaging reactions via free radicals production. Onion, Allium cepa linn, is a major source of dietary flavonoids and has used since ancient times as a food plants. Curcumin is a yellow pigment from curcuma longa, is a major component of turmeric and has commonly used as a spice and food coloring materials. Aim: the aim of the present study is to evaluate the radioprotective role of both onion and curcumin extracted as antioxidant against gamma irradiation that induced some biochemical alterations in rats. Materials and Methods: animals were pretreated with onion or curcumin by orally administration using suitable stomach tube for two weeks prior to radiation exposure. The levels of malondialdhyde (MDA), glutathione content (GSH), superoxide dismutase (SOD), glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT) and testosterone were estimated in both serum and tissues. Results: the results revealed that exposure to ionizing radiation resulted in significant elevation in the levels of MDA, GOT and GPT activities, meanwhile, showed significant depletion in GSH content and SOD activity and testosterone concentration. Conclusion: administration of onion or curcumin by using suitable stomach tube pre-irradiation has significantly ameliorated the radiation induced disturbances in all of the investigated parameters.