Abstract: The multifunctional properties of highly porous cellularmetals see attractive industrial and military applications. Recentdevelopments in the theoretical determination of effectivestress-strain relations using the method of homogenization and themultifunctional optimal design of these novel materials are reviewed. Themultifunctions include load bearing, thermal/noise management,blast resistance and structural actuating. Metallic foams with randomcellular topologies and periodic lattice metals are respectively considered.