Micron-sized magnetic microspheres with different functional groups were prepared by one-step suspension copolymerization of styrene, divinyl benzene, and methyl methacrylate in the presence of oleic acid-coated magnetic nanoparticles. In the present work, we used benzoyl peroxide as an initiator and poly(vinyl alcohol) (PVA1788; degree of polymerization: 1,700; degree of hydrolysis: 88%) as a stabilizer. We also added acrylamide (AM) monomer in the aqueous phase and methacrylic acid (MAA) in the oil phase. The morphology and properties of the resulting magnetic microspheres were examined by optical micrographs (OMs), vibrating-sample magnetometer (VSM), and Fourier transform infrared spectrometer (FTIR). The results showed the three products have uniform and spherical form with superparamagnetism and well dispersion. Moreover, we found that monomer AM had a little contribution to the copolymerization, and MAA could strikingly decrease the diameter of the final microspheres. The magnetic microspheres with functional groups could be linked well with the IgG-FITC. (c) 2007 Wiley Periodicals, Inc.