The modal pushover-based scaling (MPS) procedure, currently restricted to symmetric-plan buildings, is extended herein to unsymmetric-plan buildings. The accuracy of the extended MPS procedure was evaluated for a large set of three-degree-of-freedom unsymmetric-plan structures with variable stiffness and strength. The structures were subjected to nonlinear response history analysis considering sets of seven records scaled according to the MPS procedure. Structural responses were compared against the benchmark values, defined as the median values of the engineering demand parameters due to 30 unscaled records. This evaluation of the MPS procedure has led to the following conclusions: (i) the MPS procedure provided accurate estimates of median engineering demand parameter values and reduced record-to-record variability of the responses; and (2) the MPS procedure is found to be much superior compared to the ASCE/SEI 7-10 scaling procedure for three-dimensional analysis of unsymmetric-plan buildings. Copyright © 2013 John Wiley & Sons, Ltd.