The ongoing need to improve the efficiency and performance of grinding mills requires more detailed understanding of the dynamics of the charge behaviour, Discrete Element Methods (DEM) for simulating the flow of granular materials are increasingly being used to model such mills in order to extend this understanding. An essential part of this process is the validation of predictions from such models, Here we present detailed comparisons of the charge behaviour in a centrifugal mill predicted by DEM with high speed photographs obtained in an experimental mill. Excellent correspondence is generally obtained both for the charge motion and the power predictions. (C) 2000