Abstract : A numerical investigation dealing with dynamic rupture at a frictional interface between dissimilar materials is proposed. The numerical Finite Element model is comprised of two homogeneous and isotropic elastic solids which are brought into contact with friction by remote normal compression and shear traction. The applied shear traction is less than the required one to produce overall sliding of the two solids. The rupture is nucleated by decreasing instantaneously the friction coefficient to zero at the nucleation area. A "rupture" is considered when an initially sticking zone of the interface becomes in sliding state; after nucleation two propagating ruptures appeared. The properties (velocity, generated waves, interface state ...) of the obtained ruptures are here analyzed for a flat interface between dissimilar materials in function of the nucleation energy; then, the analysis of the effect of the interface roughness (sinusoidal asperities) is developed. The differentiated rupture inside the asperity and the conditions for coupling or uncoupling between the waves radiating in the two bodies, in function of the asperity dimensions, have been investigated. The aim of this work is to present the results from the non-linear finite element analysis in large transformations of the dynamic rupture at the interface with contact friction between two deformable bodies with and without roughness.