Blends of nylon 6 with maleated ethylene-propylene rubber (EPR-g-MA) were prepared by melt blending over the whole composition range. The reaction of the polyamide amine end groups with the grafted maleic anhydride has the potential to form thermoplastic elastomers (TPE) with controlled morphology and chemical bonding between the phases. This study focuses on the effects of nylon 6 content and crystallinity of the maleated rubber on morphological, thermal and mechanical properties of these blends. Maleated EPR with some ethylene crystallinity (H-EPR-g-MA) results in blends, which have better mechanical properties than those based on amorphous EPR-g-MA. Strain-hardening and cold-drawing were observed for both blend systems in the intermediate and polyamide-rich composition range. These effects are found to be enhanced by ethylene crystallinity in the blends. Modulus values from stress-strain measurements and dynamic, mechanical, thermal measurements are compared to predictions using a model by Hill for composite materials. Blends based on rubber with high ethylene crystallinity give better agreement with the model than those based on amorphous rubber. Phase inversion compositions derived from TEM observation, modulus measurements are compared to those calculated from the model of Avgeropoulos.