Copolymers of MMA-STY with the suitable composition, particle size distribution, and molecular weight distribution for its medical application as bone cements have been obtained by means of suspension copolymerization. The influence of the stirring rate on the final mean particle size has been established, and the scale-up of the process has been performed with successful results. The application of a kinetic model allowed to estimate the copolymer composition during the process, which is essential to obtain polymers with adequate properties. (C) 2000 John Wiley & Sons, Inc.