The plane strain compression behavior and change in mechanical properties of aluminum composite reinforced with SiC fiber have been examined. The load required for the plane strain compression was estimated with an upper bound technique and showed good agreement with experiments. During the compression tests, any fracture or cracking of specimens did not occur in the range of 60% reduction in height. Tensile strengths of the specimens decreased rapidly with the increase of the reduction; for example, 20% fall in strength after 10% reduc-tion. The modulus of elasticity, however, remained constant. It was suggested that the decrease in tensile strength was a result of disorder in fiber alignment and/or void formation at matrix/fiber interface.