This paper presents a time domain method for soil-structure interaction analysis under seismic excitations. It is based on the finite element formulation incorporating analytical frequency-dependent infinite elements for the far-field soil region. Equivalent earthquake input forces are calculated based on the free-field responses along the interface between the near- and far-field soil regions using the fixed exterior boundary method in the frequency domain. Then, the input forces are transformed into the time domain by using inverse Fourier transform. The dynamic stiffness matrices of the far-field soil region formulated using the analytical frequency-dependent infinite elements in the frequency domain can be easily transformed into the corresponding matrices in the time domain. Hence, the response can be analytically computed in the time domain. A recursive procedure is proposed to compute the interaction forces along the interface and the responses of the soil-structure system in the time domain. Earthquake response analyses have been carried out on a multi-layered half-space and a tunnel embedded in a layered half-space, and results are compared with those obtained by the conventional method in the frequency domain. Copyright (C) 2003 John Wiley Sons, Ltd.