Historically the use of new materials in aircraft construction has accounted for the major amount of mass reduction by new technology. The continuation of this role for new materials in aerospace vehicles in the 1990s is reviewed. The materials scientists' vastly increased ability to synthesize new materials and tailor mechanical and physical properties has created the need for an interdisciplinary approach among aircraft designers and materials scientists in the development of new materials. A system to assess and quantify potential benefits from aims for property improvement is described. Application of this mass-savings methodology to a typical aircraft is presented with the results associated with varying percentage property improvements in strength, stiffness, durability, damage tolerance and density. The need to obtain vastly improved corrosion resistance in magnesium alloys and higher fracture toughness in metal matrix composites is briefly discussed. Trends in high-temperature aluminium-alloy development and property comparisons with titanium are given. Carbon-fibre reinforced resin matrix composites are discussed in terms of failure modes and design allowable strain for thermoset and thermoplastic systems. Cost of current composite structure is compared with that of aluminium and approaches to reduce manufacturing cost of composites are given. General requirements are presented for high-temperature materials for hypersonic and re-usable orbital vehicles. A basic structural integrity plan for emerging materials is outlined that identifies specific technology transition needs and the related tasks that must be accomplished before new materials can be incorporated into aircraft structures.