Poly (glycidylmethacrylate-methylmethacrylate), poly(GMA-MMA) beads were prepared via suspension polymerization in the presence of ferric ions. The epoxy groups of the poly(GMA-MMA) beads were converted into amino groups during magnetization reaction, and then were grafted with methacrylic acid (MAA) via graft copolymerization. The magnetic beads were characterized by surface area measurement, swelling test, scanning electron microscope (SEM), electron spin resonance (ESR) and Mossbauer spectroscopy. The enzyme "trypsin" was immobilized on the magnetic beads via adsorption. The maximum adsorption was obtained at pH 7.0. At 2.0 mg/mL initial trypsin concentration, the maximum immobilization capacity was 123.2 mg trypsin/g beads and retained about 84.2% of its initial activity. The immobilized trypsin could not be desorbed by enzyme reaction solution in the pH range of 5.0-9.0, and could be desorbed by 1.0 M formic acid solution containing 1 M NaCl. (C) 2007 Elsevier B.V. All rights reserved.