We have derived a generalized equation for correlating the morphological parameters (matrix ligament thickness, particle spatial distribution parameter, mean particle size, particle size distribution and particle volume fraction) of polymer blends with particles obeying the log-normal size distribution. The particle spatial distribution parameters for eight regular lattices and three actual morphologies have been calculated. The particle spatial distribution parameter for the morphology of well-dispersed particles is between 1 and ca. 1.2, and is larger than those for the pseudonetwork morphology and the morphology of agglomerated particles. The relationships between the particle spatial distribution parameters defined in this work and those given in the literature are discussed.