Flexible unidirectional (UD) composite laminates are commonly being used for ballistic-resistant body armor. These laminates comprise UD layers, each constructed by laminating thin layers of high-performance fibers held in place using very low modulus binder resins, with the fibers in each layer oriented parallel to each other. As these materials are used in body armor, it is important to investigate their long-term reliability, particularly with regard to exposure to temperature and humidity as these are known causes of degradation in other commonly used body armor materials. This work investigates the tensile behavior of a poly(p-phenylene terephthalamide), or PPTA flexible UD laminate aged for up to 150 days at accelerated aging conditions of 70 degrees C and 76% relative humidity. Tests were performed at three different crosshead displacement rates and three different gauge lengths. The effect of aging on the mechanical properties of the material was observed as less than 10% degradation in tensile strength, with a more significant reduction in longer specimens when tested at slower rates.