In this paper, a novel feedback control system based on a fuzzy logic has been developed for controlling particle size of products in the dry grinding process. The system measured the particle size distribution in real time and controlled the particle size to maintain a desired set-point value. The validity of on-line particle size measurement was confirmed. It was concluded that the developed feedback system controlled the median diameter at +/- 5% of a desired set-point value under various desired set-point values and experimental disturbances. (C) 2010 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.