The mechanical properties of carbon nanofiber/epoxy nanocomposites manufactured with up to 5 wt% of carbon nanofibers dispersed in the resin via calendering approach have been measured using nanoindentation and their microstructure has been characterized by microscopy techniques. Hardness and elastic modulus of the composites measured by nanoindentation are higher than those obtained by dynamic-mechanical thermal analysis because both of the indentation size effect and the possibility of measuring zones with higher reinforcement percentage. The local mechanical properties have been correlated with the microstructure of the nanocomposites and with the tendency to the agglomeration of the carbon nanofibers. (C) 2011 Elsevier Ltd. All rights reserved.