Processability and rheological properties of the blends of poly(ethylene-Co-acrylic acid)(PEA) and epoxidised natural rubber (ENR) have been studied by a Monsanto Processibility Tester MPT). The blends were found to be miscible during reactive processing due to chemical interaction via esterification reaction at higher proportion of PEA. The rheological properties were studied at three different temperatures (120 degrees C, 130 degrees C and 150 degrees C), five different shear rates in the range from 122 s(-1) to 2452 s(-1) and at three different shear stresses (i.e., 400, 500 and 600 kPa). The melt viscosities of the blends at 120 degrees C and 130 degrees C show a positive deviation at lower shear rates and shear stress and at higher proportions of PEA and a negative deviation at higher shear rates and shear stress and lower proportion of PEA, where as at higher temperature (i.e. at 150 degrees C) of melt processing the viscosities show positive deviation (at all shear rates for all the blends) with respect to that calculated by additivity rule. This variation in melt viscosoties has been explained on the basis of chemical reaction via esterification leading to grafted structure i.e., PEA-g-ENR.