This study aims to investigate the function and impact of the reactive terpolymer (Elvaloy (R) RET) in improving the performance properties of modified bitumens. To this end, four different percentages of Elvaloy (R) RET (0%, 0.5%, 0.75%, 1.0% by weight of bitumen) were mixed with 8-100/150 grade bitumen. The physical properties of these binder samples were investigated using conventional tests such as penetration, softening point and ductility while their rheological properties were investigated using Superpave binder tests such as rotational viscosity, dynamic shear rheometer and bending beam rheometer test. The determination of high and low temperature performance grades of binder samples were supplied with the Superpave specification. The findings indicate that Elvaloy (R) RET-modified bitumens were less sensitive to temperature changes. Elvaloy (R) RET significantly improved the stiffness of bitumen. It also improved the resistance of bitumen against rutting and fatigue cracking, without causing a serious decrease in the resistance of bitumen against thermal cracking. (C) 2018 Elsevier Ltd. All rights reserved.