The effects of different types of variations in the thickness profile on the dynamic displacements and the dynamic stresses of a square plate have been investigated. The plate is assumed to be clamped or simply supported at the edges and excited by a point harmonic load at resonance. For the analysis a four-noded plate bending element has been used. The response has been determined for the first three modes of vibration. The results obtained for different thickness variations are compared with those obtained for a uniform thickness plate. It is observed that considerable reductions in dynamic displacements and/or stresses can be achieved by proper selection of the thickness variation. © 1995 by Academic Press, Inc.