This chapter reviews the advances in the materials for applications in structures of both subsonicas well as supersonic aircrafts. An account of the operating and ambient environmental conditions during flight is first given and the resulting material requirements have been discussed. Design relationships have been established taking into consideration the loading conditions and the strength requirements. In particular, the aircraft skin temperatures at various mach numbers have been taken into account for selecting appropriate structural materials for both subsonic and supersonic aircrafts; and consequently various aerospace aluminum alloys, titanium alloys, superalloys, and composites have been suggested. Finally, a new materials-selection chart is presented which would help aerospace designers to select appropriate materials for structural application in subsonic and supersonic aircrafts.