This paper deals with the characterisation of the linear viscoelastic and steady-state flow properties of commercial pigmentable synthetic binders and unmodified bitumens. From the experimental results obtained, we may conclude that both types of materials show a thermorheologically simple linear viscoelastic behaviour in the temperature range studied (5 degrees C-50 degrees C), although synthetic binders are thermorheologically complex materials in steady-state flow. Both of them display a predominant viscous behaviour within the linear viscoelasticity region. Synthetic binders are characterised by an apparent shift of the terminal zone of the relaxation spectrum to lower frequencies, probably related to the development of entanglements among macromolecule components, and by the highest values of the zero-shear-rate limiting viscosity.