A combination of the Langevin-theory-based James-Guth equation with the phenomenological C-2 term of the Mooney-Rivlin equation (modified by introducing an additional empirical parameter) is shown to represent the tensile stress-strain dependencies obtained on retraction of a number of carbon-black- and silica-reinforced butadiene-styrene networks. The stress-strain behavior at increasing strain of both pre-strained and virgin specimens is more complex but it can be satisfactorily described using the concept of a strain-dependent finite extensibility parameter (introduced previously for unfilled networks). The accuracy of data description is better than ca. 4%. Similarly to unfilled networks, the increase in the finite extensibility parameter with increasing strain is ascribed to strain-induced changes in network topology (increase in network mesh size). On retraction, such changes probably take place to a much lesser degree if at all.