This research investigates the effect of polybutadiene rubber (PBR) on chemical and rheological properties of asphalt binder with 15, 30 and 50% RAP content. SARA-separation and Fourier Transform Infraredspectroscopy (FTIR) were used to assess the chemical properties of the samples. Bending Beam Rheometer (BBR) test was applied to evaluate low-temperature performance and Dynamic Shear Rheometer (DSR) and Multiple Stress Creep Recovery (MSCR) tests were carried out to investigate high temperature performance of specimens. Results showed that the addition of PBR altered the chemical properties of the binder and led to an improvement of the rutting resistance of specimens. Despite the very low glass transition temperature of PBR, it deteriorated the low-temperature performance of samples. Moreover, some strong correlations between chemical characters (SARA – fractionation and FTIR tests) and physical parameters of the binder were found.