In this study, magnetic chitosan microspheres were prepared in a well shaped spherical form with a size range of 100 to 250 mum (size distribution +/- 15 to +/-40 mum, respectively) by the suspension cross-linking technique for use in the application of magnetic carrier technology. The magnetic material (i.e. Fe3O4) used in the preparation of the magnetic chitosan microspheres was prepared by precipitation from FeSO4 and Fe-2(SO4)(3) solutions in basic medium and then ground to the desired size (i.e. 1-5 mum). The morphological and magnetic properties of the microspheres were characterized by different techniques (i.e. SEM, optical microscopy, magnetometry). The results demonstrated that the stirring rate of the suspension medium and the Fe3O4/chitosan ratio are the most effective parameters for the size/size distribution and the magnetic quality of the microspheres, while the chitosan molecular weight (MW) has no significant effect on these properties for the given MW range (i.e. 150 to 650 kDa). The best magnetic quality of the magnetic chitosan of microspheres is around 9.1 emu/g microsphere at 10 kG magnetic field intensity. (C) 2002 Elsevier Science B.V. All rights reserved.