Micron-sized monodisperse superparamagnetic polyglycidyl methacrylate (PGMA) particles with functional amino groups were prepared by a process involving: (1) preparation of parent monodisperse PGMA particles by the dispersion polymerization method, (2) chemical modification of the PGMA particles with ethylenediamine (EDA) to yield amino groups, and (3) impregnation of iron ions (Fe2+ and Fe3+) inside the particles and subsequently precipitating them with ammonium hydroxide to form magnetite (Fe3O4) nanoparticles within the polymer particles. The resultant magnetic PGMA particles with amino groups were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), and vibrating sample magnetometry (VSM). SEM showed that the magnetic particles had an average size of 2.6 mu m and were highly monodisperse. TEM demonstrated that the magnetite nanoparticles distributed evenly within the polymer particles. The existence of amino groups in the magnetic polymer particles was confirmed by FTIR. XRD indicated that the magnetic nanoparticles within the polymer were pure Fe3O4 with a spinel structure. VSM results showed that the magnetic polymer particles were superparamagnetic, and saturation magnetization was found to be 16.3 emu/g. The Fe3O4 content of the magnetic particles was 24.3% based on total weight. (c) 2005 Wiley Periodicals, Inc.