This paper studies experimentally the creep behaviour of particle-reinforced Mooney-Rivlin rubber composites (PR-MRC). The specimens were made of hydroxyl-terminated polybutadiene (HTPB) cured with toluene-2,4-diisocyanate (TDI) as the matrix, and contained 0 to 40% volume fraction (f(1)) of inclusions. They were subjected to uniaxial tensile and constant-loading creep tests. Results show that the material behaviour does indeed display the characteristics of Mooney-Rivlin material and that Eyring’s reaction rate principle is suitable to describe the viscoelastic behaviour of this rubber composite. Hence, the Boltzmann superposition technique cannot be applied to solve the creep problems of these rubber composites. Although Findley et al. (1976) have proposed the multiple integrals form, solving this form is complicated and does not guarantee convergence. In order to describe the creep behaviour of Mooney-Rivlin rubber composites, we have extended the So-Chen formulation of the nonlinear four-element Burger’s (NFEB) model, which describes the nonlinear stress-strain relationship of neo-Hookean rubber elasticity. This avoids the above-mentioned difficulty and an analytic solution is obtained, which is in good agreement with the experimental results.