Scouring of pile groups is a relatively common phenomenon that can produce damage, particularly for river bridges subject to seismic hazards. This paper reports the results of an experimental investigation of the seismic failure mechanism and post-earthquake vertical load-carrying capacity of scoured pile group foundations. Three identical 2 × 3 reinforced concrete (RC) pile group specimens were embedded in homogeneous medium density sand with an over- all scour depth equal to five times the diameter of a single pile. These specimens were subjected to lateral cyclic loads of different amplitudes to produce a predetermined damage state in the piles. Pushover in the vertical-downward direction was then applied to these damaged specimens to evaluate their residual load-carrying capacities. Experimental results showed that the leading pile was more prone to seismic damage. The extension of pile damage also had a significant influence on the residual vertical load-carrying capacity and the corresponding vertical failure mode of the pile group. To quantify the parameter sensitivity of the seismic performance for scoured pile group foundations, an efficient finite element model (FEM) of pile groups was proposed based on a beam on nonlinear Winkler foundation approach. This FEM used asymmetric p-multipliers to describe the difference in soil resistance exerted on leading and trailing piles when cyclic lateral loads are applied. The proposed FEM was validated through a comparison of the numerical response with the experimental measurements. The proposed FEM was able to capture both the global and local structural responses of pile group foundations. The pile group foundations were found to have considerable ductility capacity. Pile diameter and axial load ratio of piles were the most important parameters for the seismic performance of pile groups. Based on the results of this parametric analysis, recommendations are proposed for the seismic design of pile group foundations with scour effects.