The influence of different vibration parameters on the rheological properties of filled bitumen systems has been considered. The criteria for the effect of vibration on such systems have been determined. It has been shown that vibration leads to a sharp drop in viscosity, close to the limiting value, at small deformation rate gradients and that it causes an increase in viscosity with the deformation rate. The observed phenomenon has been called 'vibration dilatancy'. The laws governing the appearance of this phenomenon in filled bitumen systems have been formulated. An attempt has been made to explain vibration dilatancy.