The effect of the deconvolved stochastic seismic excitation on the nonlinear response of dam-foundation interaction systems is investigated in this paper using the equivalent linear method. For this purpose, three different earthquake input mechanisms are used: the standard-rigid-base input model, the massless-foundation input model and the deconvolved-base-rock input model. The spatial variability of ground motion including the incoherence and wave-passage effects are taken into account in the analyses. The limit earthquake in 1999 is selected as sample ground motion. Two-dimensional interface finite elements are used between the dam-soil deposit and the asphalt face and also between the foundation-soil deposit and the cutoff wall. The mean of the absolute maximum displacement and stress values obtained from the three earthquake input models are compared with each other.