The tensile behavior, erosion/impact resistance, mechanical fatigue strength, thermal fatigue behavior, and creep strength of filamentary reinforced aluminum and titanium alloy matrix composites were briefly compared. Parallel to the filament direction, aluminum matrix composites are slightly stronger than titanium matrix composites up to a temperature of about 600°F (314°C). Titanium matrix composites, however, have shown significant off-axis strength advantage even at room temperature. B/SiC-Ti has shown a five-fold advantage in transverse strength over B-A1 at a test temperature of 500°F (260°C). The erosion rate of fiber-reinforced composites was found to be controlled by the matrix until the filaments became exposed. The titanium matrix, having an order-of-magnitude stronger matrix yield strength, exhibited greatly improved ballistic impact resistance, when compared to the aluminum matrix system. The low-cycle fatigue strength of titanium composite was superior to that of comparable aluminum composite. On the other hand the high-cycle fatigue strength in the 0 deg orientation for the titanium composite was significantly lower than that of a comparable aluminum composite. The resistance to thermal fatigue damage, when measured by tensile strength degradation, delamination, and dimensional distortion, was in favor of titanium composites. The transverse creep strength of B/SiC at 800°F (427°C) was shown to be ten times better than that of B/SiC-A1 at 575°F (302°C).