The effect of mechanically-induced surface damage on the comminution behavior of a number of particulate materials was investigated using the Ultra-Fast Load Cell (UFLC) device. The use of smooth spherical particles facilitated the monitoring of damage evolution. Particles were subject to low-energy milling treatments to generate different levels of surface damage prior to being individually fractured in the UFLC. Increased levels of surface damage caused a reduction in particle fracture energy and strength in some materials, but also resulted in a coarser progeny size distribution. Observations made on progeny fragments suggest that Hertzian fracture is often the precursor of a more complex mode of failure. The extent of the surface damage development was quantified using optical image analysis on sectioned particles. Materials with initially small defect distributions were found to experience the greatest change in their comminution characteristics, whereas materials with significant prior damage showed little change in their behavior. The severity or sharpness of the surface flaws was found to be important in determining the particles comminution response. Surface damage at very low levels was also found to have a small strengthening effect on some materials which may have some implications for the design of an optimal comminution strategy and equipment used to perform it. (c) 2007 Elsevier B.V. All rights reserved.