Meso (effect of grain size) and macroscopic ( effect of sample dimension) considerations about damage accumulation processes are discussed. Although both factors may significantly influence damage accumulation kinetics, they are not taken into account in most of currently used models. The role of meso and macroscopic factors may be explained in the framework of a recently developed model of damage accumulation (Multi-Step Damage Accumulation - MSDA), which assumes that the damage build-up can be regarded as a sequence of structural transformations triggered by the destabilization of the current structure of a crystal induced by radiation damage. (C) 2009 Elsevier B. V. All rights reserved.