In this report, magnetic Fe 3 O 4 nanoparticles were functionalized with chitosan-grafted-poly(ethylene glycol) methyl ether (CTS-mPEG) for paclitaxel (PTX) delivery. The Fe 3 O 4 nanoparticles were prepared via the chemical coprecipitation method and then coated with CTS-mPEG (Fe 3 O 4 @CTS-mPEG) by a simple method. The formation of Fe 3 O 4 @CTS-mPEG was characterized by several methods including proton nuclear magnetic resonance spectroscopy, Fourier transform infrared, and X-ray diffraction. Furthermore, the superparamagnetic properties of Fe 3 O 4 @CTS-mPEG were demonstrated by a vibrating sample magnetometer; the saturation magnetization reached 23 emu g -1 . The sizes and morphologies of Fe 3 O 4 and Fe 3 O 4 @CTS-mPEG nanoparticles were determined by transmission electron microscopy. The result indicated that Fe 3 O 4 @CTS-mPEGs were nearly spherical in shape with an average diameter of 20 nm, compared with the 12-nm Fe 3 O 4 particles. Especially, PTX was effectively loaded into the coated nanoparticles, 86.9±3.4% for drug loading efficiency, and slowly released up to 120 h. These results suggest the potential applications of Fe 3 O 4 @CTS-mPEG in the development of stable drug delivery systems for cancer treatment.