Exploratory investigation of filament-metal matrix composites received a significant impetus several years ago from the development of high modulus, high strength continuous filaments, and the growing availability of whisker fibers. First generation attempts to prepare and study the behavior of such composites has led to a clearer but still incomplete definition of the potential value of these systems and of the principal problems to be overcome. An analysis of future use potential must consider possible competition from the more familiar directions of metallurgical development or polymer matrix composites. Currently, the most unambiguous potential for future use is at temperatures above 1600 to 1800 F. This range represents an “oxidation barrier” for ductile structural materials. The future use potential at lower temperatures where polymer matrices can be considered, up to about 700 F, is much less clearcut. Here, the possible advantages of a metal matrix involves concepts such as improved abrasion and erosion resistance, and providing interlaminar shear strength and resistance to complex stress states in general without requiring precise and complex filament orientations. Problems in filament-matrix compatibility continue to be the principal difficulty to be overcome for metal matrix composites. However, in the boron-aluminum system there has been sufficient progress in preparing a sound composite without destructive interaction, with stability over time and temperature ranges of some practical interest, to warrant further development. For high-temperature applications, a more sophisticated examination of reinforcement and matrix components in chemical interaction and interdiffusion and their effects on composite properties as a function of temperature, time, and environment is required.