An attempt of application of a structural approach in evaluation of viscoelastic properties of two polyester based concretes and their matrices-polymer resin filed with minerals at various filler volume content-was undertaken. It was found that the approach can be used in evaluation of the creep compliance curves of the composites under compression either in conditionally initial state or after aging. The results of calculation by Kerner's model and the generalized Christensen's model are in close agreement. They gave good description of the experiment. The higher calculated values of the elastic moduli of the composites than the experimental values were obtained. A better description is obtained using Kerner's model of composite consisting of the resin (matrix) and filler (small-and large-dimensional particles). The application of the structural approach for description of elastic and viscoelastic properties of the composites made it possible to evaluate interphase properties and content and porosity of the composites and their changes during creep.