A number of researchers have studied aggregate characteristics including elogation, flatness, and other shapes that are belived to effect asphalt mixture properties such as internal resistence, rutting resistance, tensile strenght, and complex modulus etc. However the aggregate modulus also affects the asphalt mixture modulus significantly, wich has not been taken into consideration. In this paper, the effect of aggregrate particle-to-particle interaction was studied trought numerical modeling using the discrate element modelling (DEM) approach. The individual material phases (e.g., aggregrates and mastic) were modeled with clusters of discrete elements based upon laboratory testing of the individual phases. For a given set of material parameters for each phase, the degree of particle-to-particle contact in an asphalt mixture was found to have a profound influence on overall mixture modulus. A parametric investigation of aggregrate modulus revealed that the contribution of aggregrate modulus to overall mixture modulus was very significant. Pending further experimental verification on asphalt m,ixtures, this finding may shed new light on the importance of aggregrate stiffness on overall mixture properties.