The paper presents the method of analysis and a comparison of the effectiveness of modified and conventional syntactic foams. The method employs the two-phase superposition approach recently developed for composite materials consisting of several concentric phases. Conventional syntactic foams consisting of spherical voids surrounded by thin glass shells embedded in the matrix are compared to modified foams with cylindrical or spheroidal voids. Modified syntactic foams analyzed in the paper include foams with cylindrical voids aligned along the applied stress or perpendicular to the stress and foams with randomly oriented cylindrical voids. It is demonstrated that while conventional syntactic foams with spherical voids absorb more energy than their modified counterparts, the stiffness of such foams is compromised due to the presence of voids to a larger degree than in modified foams. Accordingly, modified syntactic foams may appear a better compromise if a high energy absorption has to be combined with a prescribed large stiffness of the material.