Laboratory drop weight tests rig and numerical modelling have been used to investigate theimpact energy effect on the degree of dynamic fragmentation of cylindrical rock samples. Thedrop weight tests indicated that the degree of dynamic fragmentation of the African Noriteformed a non-linear relation with impact energy. In the numerical modelling of the dropweight test, the shear localisation developed in the African Norite was assumed to representdiscrete fracture planes. Shear bands, outputs of the image analysis of the numerical model,were used to separate solid material from shattered or broken material, allowing the FLACoutput from the dynamic modelling to be processed into black and white fragmented images.This was undertaken to determine particle size distributions. Corresponding grading curvesfrom the numerical modelling were then validated against the laboratory derived curvesindicating the potential of numerical modelling to simulate the process of rock fragmentation.