Abstract: The high-porosity cellular metals and the related sandwich structures are a new type of light-weight structural and functional material/structure. They are attractive for their high specific strength, high specific stiffness and excellent energy absorption capability. This paper reviews various processing techniques, the mechanical performance and the application fields of the sandwich structures with cellular metal cores. The mechanical behavior of metallic sandwich structures, including beams, plates and shells, subjected to quasistatic and dynamic loads is discussed, including theoretical predictions, numerical simulations and experimental results. The discussion also includes the deformation/failure, the dynamic response and the energy absorption of sandwich structures.