The behaviour of infilled frames subjected to in-plane loading has been extensively studied, whereas few studies have been done on the behaviour of infilled frames under the action of combined in-plane and out-of-plane loads. In this paper, the effects of out-of-plane loads on the in-plane behaviour of infilled frames are investigated. Pushover analysis is performed with a detailed discrete model using 3-D elements incorporating damage-plasticity material models established by ABAQUS. It is found that the diagonal bracing action of the infill wall to the bounding frame can be significantly softened by out-of-plane loads owing to the P-δ effect. The in-plane load capacity of infilled frames can then be reduced up to 30% under the action of out-of-plane loading.