In this paper the structure response of quasi-statically loaded sandwich beams made of aluminum skins with open-cell aluminum foam cores is investigated experimentally. The experimental programme was designed to investigate the deformation and failure modes of sandwich beams, so a large number of experiments have been conducted, and the experimental results are reported and discussed systematically. It is found that sandwich beams under quasi-static punching loads can fail in several modes: face yield, face wrinkling, core shear, the bottom face fracture and interfacial failure between the core and the faces. Moreover, the effects of face thickness, cell size of foam material on the failure and deformation modes were discussed. The experimental results are of worth to optimum design of cellular metallic sandwich structures.