A modification of the Mori-Tanaka method is proposed to evaluate the average elastoplastic behavior of composites and polycrystals in a virtual matrix. The virtual matrix is an elastic material in which real matrix material and inhomogeneities are embedded, and its volume vanishes as a limit after homogenization. With regard to elasticity, depending on the choice of material properties of this virtual matrix, many kinds of average moduli between the classical bounds can be predicted. In this paper, we extend the application of this method to elastoplastic materials. Furthermore, Weng's approximate model of interfacial debonding between the inclusions and the matrix is installed, because of its very simple criterion for the initiation of debonding to simulate progressive debonding phenomena. Several numerical examples without interfacial debonding show the applicability of the virtual matrix concept to elastoplastic materials. The characteristics of the model and its overall behaviors are described through the use of typical numerical simulations with debondings. Finally, comparisons with experimental results including debondings demonstrate the eligibility of the proposed method and models, and the application of the present method to designing a hybrid FRP is overviewed. (C) 2011 Elsevier Ltd. All rights reserved.