Magnetic nanomaterials are making significant impact on improving the quality of human health that is tangible from a wide range of applications in various fields of medicine and biology. In recent years, nanoparticles successfully demonstrated outstanding applications due to having excellent magnetic properties of the iron oxide nanoparticles-based counterparts. Zero-valent iron nanoparticles toxicity is less than the toxicity of other nanoparticles. These nanoparticles are considerably potential for functionalization due to their highly reactive surfaces and this feature can facilitate targeted functionalization. This is very promising for various applications in different fields. Use of polymers as a protective agent is increasing sharply. Polymer magnetic field of zero-valent metal nanoparticles is still in its early stages. In this study, the syntheses of zero-valent iron nanoparticles are presented in different ways. Nanoparticles can be identified and evaluated through their size, shape, morphology, syntax, and various laboratory methods. In this context, magnetic nanoparticles can be potentially used in hyperthermia, magnetic resonance imaging (MRI), diagnosis and treatment of tumor diseases or cancer, labeling, biological separation, biotechnology, and eliminating major organic, inorganic and radioactive pollutants because of their high biocompatibility. With respect to the importance and the need to draw the attention of researchers to zero-valent iron magnetic nanoparticles, a brief description of various methods of synthesis, characterization, and their application in medicine and biology are reviewed.