Iron oxide nanoparticles have been widely used experimentally for numerous applications such as magnetic resonance imaging contrast enhancement, tissue repair, immunoassay, detoxification of biological fluids, hyperthermia, drug delivery, cell separation, treatment of iron deficiency anemia etc.Due to their extraordinary reduction capabilities, small size in the range of several tens of nanometers and high reactivity with a broad spectrum of toxic substances, these ultrafine particles are highly applicable in the reduction technologies of ground water remediation and waste water treatment. Nanoiron has attracted a great deal of attention in nanomedicine over the past decade. Ferumoxytol is a novel intravenous nanoiron product that can be administered in treatment of iron deficiency anemia. Iron oxide nanoparticles have proven to be highly effective contrast agents for the magnetic resonance imaging diagnosis of a variety of diseases and pathologic processes.