This paper presents a method for 3D elastic wave scattering analysis by an obstacle in a thick plate. The method is a coupling method of the boundary element method (BEM) and the generalized ray theory (GRT). For computational efficiency,the free field displacement in a plate is calculated by the GRT, and the solution is used as an incident field in the successive BEM analysis. The displacements or the tractions on the surface of the scattering object are obtained by the BEM. The boundary values obtained thus are then substituted into the integral expression of the scattered waves, in which the Green’s functions are evaluated by the GRT to reduce computational cost further. As a numerical example, the scattering by a spherical cavity embedded in a plate is solved. The numerical results are shown for displacement waveforms as a function of time at points on the cavity and plate surface. Through the numerical example, benefit of the proposed method is discussed. © 2003 American Institute of Physics