The aim of this paper is to investigate the site-response effect on the transient stochastic seismic response of concrete dams to spatially varying ground motion. The dam model considers the dam-reservoir-foundation interaction effects. For this purpose, variable-number-nodes two-dimensional fluid finite elements based on the Lagrangian approach were programmed in the FORTRAN language and incorporated into a general-purpose computer program, SVEM, which was used for stochastic dynamic analysis of solid systems under spatially varying earthquake ground motion. The spatial variability of ground motion was taken into account with the incoherence, wave-passage and site response effects. Stationary as well as transient stochastic seismic analyses were performed for the selected dam. A time dependent frequency response function was used throughout the study for transient stochastic analysis. Displacements, stresses and hydrodynamic pressures occurring on the upstream face of the dam were calculated for each component of the response. It was observed that stationarity was not affected by changing site conditions; however, site effects increased the response values.