Magnetic nanoparticles are the good choice for using in MRI as the contrast agent. Iron oxide particles such as magnetite (Fe3O4) or its oxidized form maghemite (γ-Fe2O3) are the most commonly employed in biomedical applications. In this study, we synthesized and optimized the preparation of chitosan manganese-ferrite nanoparticles (CMn-Fe nps) and evaluated its ability for the mice macrophage cells imaging with MRI. The core and hydrodynamic size of the nanoparticles was 54±27 nm and 149±48 nm respectively. The magnetization reached a saturation magnetization value of 95 emu/g. The MRI images showed that the liver and some other organs were accumulated the CMn-Fe nps and produced a negative contrast in images. CMn-Fe nps demonstrated that it is a good candidate for using as a contrast agent material in macrophage cells imaging with MRI.