Blends of polypropylene (PP) and ethylene propylene rubber (EPR) were studied. The effect of the level of rubber addition and the ethylene content is described. The results show that the viscosity of the PP, rubber content, ethylene content, and grafted EPR by maleic anhydride (MA) are important factors in controlling the blend properties. The miscibility and dynamic properties of the blends were studied by DMTA. Impact and tensile properties were also studied. SEM was used for the investigation of the phase morphology and rubber particle size and particle-size distribution.