Com. coal tar pitch was modified by addn. of poly(ethylene terephthalate) at 260 degrees C for 30 min (10-50% by mass). The blends were studied for rheolog. properties (viscosity, characteristic temps., elastic and viscous modulus, flow curves). The addn. of poly(ethylene terephthalate) resulted in an increase in bitumen viscosity and its resistance to shear, thermal resistance and softening temp.