Iron is a vitally essential element for the maintenance of health in the living organism however; iron overload can have harmful effects on health. Nanoparticles constitute a therapeutic approach for the remedy of many disorders. So the study was performed to examine the potential ameliorative effects of cerium oxide nanoparticles (CeONPs) against ferrous sulfate (FS) induced oxidative stress, hepatic, renal and thyroid functional disorders in rats. Twenty-eight male albino rats were equally assigned into four groups. Group1 received 1 ml saline (control), FS group rats received ferrous sulfate (30mg/Kg/day), CeONPs group (0.5mg/Kg/day) and the fourth group received CeONPs + FS (0.5mg/Kg + 30mg/Kg). Rats in all groups were injected intraperitoneally for two weeks (5 days/week). Results revealed that FS increased serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), total bilirubin, total protein, creatinine, and urea. In addition, hepatic and renal levels of malondialdehyde (MDA) were increased while glutathione (GSH), superoxide dismutase (SOD) levels in the liver, kidney and serum thyroxine level were reduced. Treatment with CeONPs restored liver, kidney and thyroid functions to almost the normal levels and improved the oxidant – antioxidant status. So the study pointed to the ameliorative effect of CeONPs against Fs-induced disorders on oxidative stress, liver, kidney and thyroid function.