The beta-alpha polymorphic transition in plastically deformed isotactic polypropylene (iPP) was characterized by means of microindentation hardness. For this purpose microindentations were mapped onto the surface of the necking zone of a tensile loaded injection molded beta-iPP "dumb-bell" specimen. Results evidence a sharp decrease of the H-values instead of the expected H-increase due to the beta-alpha polymorphic transition. Far away from the necking zone an H-increase is detected. It is shown that the destruction of the starting isotropic spherulitic structure and the decrease of crystallinity in the necking zone gives rise to lower H-values. However, at larger distances from the neck, the emerging fibre structure induces a better chain orientation that results in a slight H-increase. Analysis of the isotropic and necked samples before and after their annealing using DSC and WAXS supports the assumption regarding the role of the microvoids in decreasing the hardness value.