Wet ultrafine grinding has been increasingly used for production of ultrafine powders in various industries. It has been known that slurry theology significantly influences the grindability of industrial minerals in wet ultrafine grinding. This review represents some previous work with respect to slurry theology in ultrafine grinding. In this review, some methods for the characterization of the slurry theology and some empirical equations modelling theological behaviours of slurries were presented. The semiempirical model incorporating slurry theology, solids concentration, particle size and slurry temperature was described. In addition, on-line measurement for the slurry theology control was also discussed. In the case of ultrafine grinding, various parameters (such as solid concentration, particle size and distribution, particle shape, temperature, rotation and pH, use of dispersants), which affect the slurry theology, have been described. It was revealed that the optimization of the rheological behaviours of slurry in ultrafine grinding could increase throughput, energy efficiency and product fineness as well. It is suggested to further study the mechanisms of slurry theology in the presence of chemical dispersants in wet ultrafine grinding. It is desired to develop a model, which can represent a relation among slurry theology, comminution parameters, amount of dispersant, energy efficiency and particle size characterization. (C) 2004 Elsevier B.V. All rights reserved.