Metal matrix composites are gaining increasing attention in materials research and attracting engineers as a candidate material for future applications. This investigation demonstrates the tensile fracture and fatigue behavior of continuous γ-alumina fiber (Altex) reinforced aluminum matrix composite, i.e., γ-Al2O3 (Altex) / Al that was fabricated by a squeeze casting process. Special attention was paid to the environmental influence of vacuum. Fiber reinforcement increased tensile strength, elastic modulus and fatigue strength. At lower stress levels, the fatigue strength of a [0°] specimen at a stress ratio R of -l decreased from that at R = 0.05, because an initiated longitudinal crack promoted microbuckling of fiber at R = -1. However, at higher stress levels, the strength at R = -l equaled that at R = 0.05. The fatigue strength of a [90°] specimen in vacuum was higher than that in air, although the tensile strength was the same. The composite had strong fiber / matrix interfacial strength and therefore, the matrix cracking was dominant in the [90°] specimen, leading to a higher fatigue strength of the matrix in vacuum. In contrast with these, the tensile and fatigue strength of a [0°] specimen was increased in vacuum, because the fiber strength was increased. Single fiber tests showed that fiber strength increased with decreasing water content in an environment and with increasing displacement rate. The mechanisms of tensile and fatigue fracture as well as influences of vacuum were discussed.