The nonlinear rheology of styrene-butadiene rubber filled with carbon-black or silica particles is investigated by complementary viscosimetric devices on a wide range of deformation and deformation rates. The effect of filler volume fraction on the rheological behavior is systematically studied. The importance of a critical volume fraction (percolation threshold) is outlined, giving rise to a network structure at rest. At finite deformation, this Structure is destroyed and the compounds exhibit a nonlinear rheology quite similar to the unfilled rubber. The separability of time and strain effects on the relaxation modulus is observed not only for the pure elastomer. but also for the filled compounds. Several viscoelastic functions of the filled compounds (linear viscoelastic moduli, damping function, and shear stress) can be rescaled using a concentration shift factor that is identical to the one used in Newtonian suspension rheology. (c) 2006 The Society of Rheology.