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. Development of radioprotectants and mitigators is the therapeutic approach to ameliorate the negative health impact of radiation exposure. The majority of substances with biological activity used in medicine are produced by actinomycetes and fungi. Aim: the aim of the present study is to evaluate the radioprotective role of the antimicrobial active metabolite of Streptomyces atrovirens Rahman as antioxidant against gamma irradiation that induced some biochemical alterations in rats. Material and Methods: animals were pretreated with antimicrobial active metabolite of Streptomyces atrovirens Ab1 using suitable stomach tube for two weeks prior to radiation exposure. The levels of malondialdhyde (MDA), glutathione content (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutamic oxaloacetic transaminase (ALT), glutamic aspartate transaminase (AST), alkaline phosphatase (ALP) and gamma glutamyl transferase (GGT) activities, also total cholesterol (TC), triglyceride  (TG), high density lipoprotein cholesterol (HDL-C),  and low density lipoprotein cholesterol (LDL- C) were estimated. Results: the results revealed that exposure to ionizing radiation resulted in significant elevation in the levels of MDA content, ALT, AST, ALP and GGT activities and concentration of TC, TG and LDL-C, meanwhile, showed significant depletion in GSH content and SOD, CAT and GPx activities and HDL-C concentration. Conclusion: it could be concluded that, the administration of the antimicrobial active metabolite of Streptomyces atrovirens Ab1 pre-whole body gamma irradiation resulted in sufficient amelioration against radiation effects on the biochemical aspects examined in the present study.