The microindentation hardness studies of crystalline polymers carried out in the last few years have aimed to detect the textural and morphological changes in these polymers [1]. As plastic straining produced by microindentation measurements is confined to a few micrometres at the polymeric surface, this nondestructive technique is a powerful tool to study surface modifications [2] as well as structural changes in the whole mass of a homogeneous polymer [1]. On the other hand, the determination of storage and loss parts of the complex moduli of polymers by means of dynamic mechanical analysis is a wellestablished approach to the understanding of viscoelastic properties of polymers [3]. The results of dynamic mechanical measurements allow one to locate the viscoelastic relaxations of polymers, to study the influence on them of many structural parameters (crystallinity, crosslinking, orientation, plastification) and to provide an alternative route for research on technological topics such as composite structure, adhesion and peeling, friction, acoustic damping and impact strength [4]. The variation of this last property as a function of temperature has been correlated with dynamic mechanical results. In some polymers such as polytetrafluoroethylene, the trends in the plots of impact strength and loss factor against temperature are quite similar [5]. The theoretical explanation of this remarkable parallelism is, however, rather elusive, because dynamic mechanical measurements are founded on principles of linear viscoelasticity whereas impact strength determinations are clearly based on nonlinear phenomena. Notwithstanding this, both measurements deal with dissipation of elastic energy, thus justifying the phenomenological parallelism. Microindentation hardness values are related to deformation and recovery of a material under load. This load can be considered as a microimpact and the results of the microindentation should correlate with the values of dynamic moduli. The apparent absence of studies of this correlation, prompted us to measure the microindentation hardness and the dynamic moduli of polypropylene in the temperature range between 20 ° and 20 ° C, in which the glass transition of this polymer takes place. Microhardness measurements have been performed by a Vickers indentor attached to a Universal research