Dynamic stress-softening was studied under relatively low deformation with a series of vulcanizates filled with silica and carbon blacks. When strain sweeps are repeatedly applied on the samples, G＇ and G " are substantially reduced and loss tangent and loss compliance are essentially increased. Almost all stress softening is achieved in the first strain sweep. Upon aging at room temperature, the softening effect can be partially recovered. Dynamic stress softening also shows a strong dependence on temperature and frequency as well as on rubber compounding, filler systems in particular.