This paper provides an overview of how the surface properties of ferromagnetic nanoparticles dispersed in fluids is modified by natural and biocompatible polymers. Among common magnetic nanoparticles, magnetite (Fe3O4) and maghemite (g-Fe203) are popular candidates because of their biocompatibility. Natural polymeric coating materials are the most commonly used biocompatible magnetic nanoparticle coatings. In this paper, recent progresses in the methods of ferrofluids surface modification by the common natural polymers consisting of dextran, chitosan, gelatin and starch are reviewed.