Owing to its intensive mass and heat transfer ratios and its coupling of the process stages of drying, shaping and homogenization as well as classification, continuous fluidized bed-spray granulation drying has gained acceptance as a thermal treatment process for granular solids. In this study, a balance of the particle populations is completed for a continuous fluidized bed-spray granulation with external classification. Thus, it ought to be possible to describe the particle size distributions changing over time in the fluidized bed and in the product flow [Powder Technol. 82 (1995) 37; H. Uhlemann, L. Morl, Wirbelschicht-Spruhgranulation, Springer Verlag, 2000, ISBN 3540-66985-X.]. (C) 2003 Elsevier Science B.V. All rights reserved.