Abstract: In order to rationally evaluate the ultimate load-bearing capacity of masonry-infilled frames, a new method based on the two-parameter unified strength theory is proposed for the failure mode that usually appears in practice. This method takes into account the shear stress between the infilled masonry and the peripheral frame members, the tension-compression strength difference and the second principal stress of the masonry material, the geometric aspect ratio of structures, and the relative strength of the infilled masonry compared to frame members. Testing data of six laboratory models are presented. The results estimated with the proposed formulae are shown to agree favorably with testing results. Furthermore, several evaluation methods introduced in literatures for the ultimate load-bearing capacity of masonry-infilled frames are discussed.