The inelastic response of a one-storey system with two-way eccentricities and subjected to bidirectional spatial earthquake ground motion is analyzed in this paper. 20 sets of bi-directional spatially varying horizontal earthquake ground motion time histories are numerically simulated for the analysis. The simulated motions are compatible individually with Newmark-Hall design response spectrum with 5% damping and normalized to 0.5g, and are compatible with an empirical coherency loss function between each other. Ensemble mean responses of the system to 20 sets of ground motions are estimated. Effects of system parameters such as uncoupled torsional-to-lateral frequency ratios, stiffness eccentricities in both directions, as well as the spatial ground motion wave passage effect, on coupled inelastic torsional-lateral responses are investigated. Numerical results are presented in dimensionless form. They are also compared with the code torsional provisions. For comparison purpose, some results obtained with linear elastic analysis are also presented.