The mechanical and dynamic mechanical properties of blends of poly(ethylene-co-acrylic acid) (PEA) and epoxidized natural rubber (ENR-50) have been studied after reactive blending in various proportions in a Brabender Plasticorder. The miscibility of the blends has been studied by using a computer simulation method and experimentally confirmed by dynamic mechanical analysis. The dynamic properties of the blends exhibit single glass transition temperature (T-g) values, thus conforming to the law of miscibility. A positive deviation from the Fox equation (theoretical T-g) is a Clear indication of miscibility via chemical interaction. A new beta-transition peak in the blends appeared, and this is assumed to be due to the side-chain ester group vibration, confirming a chemical reaction between the in situ generated -OH groups of the ENR and free -COOH groups of the PEA. This leads to miscibility between the constituents forming the grafted structure, i.e. PEA-g-ENR. The mechanical properties exhibit a synergism above that calculated via the additivity rule. The chemical interactions have been further confirmed by swelling studies in a common solvent.