Ion irradiation is frequently used to tailor functional properties of materials or to simulate the effects caused by ionizing radiations. In both cases the evolution of the mechanical properties of materials upon irradiation is of crucial importance. However, reliable and quantitative determination of the mechanical properties of irradiated materials is a rather complicated task. In this paper a discussion of the methodology used for nanomechanical measurements of irradiated layers is presented with a special emphasis on the description of possible experimental errors. The possibilities offered by nanornechanical studies for the interpretation of structural transformations in irradiated materials are also discussed. The study has been performed on irradiated Sic and MgAl(2)O(4) crystals. (C) 2009 Elsevier Ltd. All rights reserved.