Ionizing radiation generates reactive oxygen species that induce oxidative stress, which generates free radicals, which associated with many degenerative diseases. The present study has been designed to evaluate the ameliorative role of aqueous moringa oleifera leaf extract (MO) against γ-radiation (IRR)-induced oxidative stress in hepatic and renal tissues in rats. Twenty four male albino rats were divided into four groups, (1) control group injected with the vehicle, (2) MO treated group, (3) IRR group, (4)MO/ IRR treated group. Biochemical and ultra structural examinations were utilized for evaluation of the oxidative stress, hepatotoxicity and nephrotoxicity. IRR (6Gy) caused a significant increase in liver and kidney malondialdehyde (MDA) and total nitrate/nitrite (NO (x)) levels and significant decrease in superoxide dismutase (SOD), catalase (CAT) activities and glutathione (GSH) content. The activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), and the levels of urea nitrogen and creatinine in serum were increased. Administration of MO (300 mg/kg, i.p.) for 15 days prior to IRR ameliorated the hepatotoxicity and nephrotoxicity induced by IRR. Ultra structural examination of liver and kidney tissues confirmed the biochemical data. The present results revealed that MO has a protective effect against IRR-induced hepatotoxicity and nephrotoxicity through its free radical scavenging activity and enhancement of the antioxidant defense mechanisms.