In this article, the dynamic mechanical properties of a multiphase system containing a dispersed phase with complex morphology is discussed with respect to the microstucture of the dispersed phase. The samples are prepared by emulsion blending of matrix particles (MP) and particles for a dispersed phase that are obtained with heterocoagulation techniques. The heterocoagulated particles were prepared using two kinds of particles of different sizes : small negative particles (SP) and large amphoteric particles (LP), taking advantage of their opposite surface charge in the colloidal state. To vary compatibility between SP and LP, two kinds of small particles were used : poly( methyl methacrylate - butyl acrylate - acrylic acid) and poly( styrene butyl acrylate-acrylic acid) (SP-M and SP-S). Dynamic mechanical behavior of simple blends composed of MP and SP were also measured to examine the effect of microstucture.