The free vibration response of a simply supported sandwich composite plate with syntactic foam core is analyzed using a multiple scales asymptotic method. No apriori assumption is made on the through-thickness variation of the field variables. The formulation transforms the basic 3-D equations of elastodynamics into recursive sets of equations for different orders of approximation. The lowest order approximation corresponds to the classical plate theory and higher order approximations include effects of rotary inertia and shear deformation. The influence of the size, thickness and volume fraction of inclusions on the natural frequency of the plate has been studied. The variation of the interlaminar stresses through the thickness is also presented.