In recent years, extensive researches were devoted to iron oxide nanoparticles (IONPs), including magnetite (Fe3O4) and maghemite (γ-Fe2O3), due to their low toxicity and cost, in addition to their unique physicochemical and magnetic properties. In this review, we present a brief introduction on IONPs in terms of classification and properties. Because the synthesis approach and surface modification are found to be key factors for better control of particle morphology and shape, as well as to produce monodispersed IONPs, which have direct influence on their properties and applications, particular emphasis will be given to the chemical synthesis methods and surface modifications by several organic materials such as polyvinylpyrrolidone (PVP), chitosan, and cetyltrimethylammonium bromide (CTAB). Recent trends and future prospects in this research field are also discussed. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.