The potential of metal matrix composites is discussed, after an introduction to the underlying principles of fibre reinforcement. The unique properties of composite materials, specifically high strength and modulus to weight are discussed. The advantages of metal matrix composites over other types of composite materials and competing homogenous materials are presented. Metal matrix composites are seen to be superior in many areas, but most specifically in severe environments of temperature, vacuum and stress. A brief review of the present status of the micromechanical theory of composite behaviour illustrates the relatively primitative stage of its development. The reinforcing fibres available for the construction of composites are presente...