An environmental testing was conducted on polymeric nanocomposites fabricated by dispersing the carbon nanotubes (CNTs) into polymeric epoxy resins in order to determine their shelf life, reliability, stability, as well as other property changes as a function of temperature and humidity. In this study, various multi wall CNTs (∼140 nm diameter and ∼7 μm length) ranging from 0.5% to 2.0% were initially dispersed in ethanol using a magnetic stirrer, and then an epoxy resin was added to the mixtures under continuous stirring. When the solvent completely evaporated after 18 hours of stirring, a hardener was added to the dispersion. The mixtures were then poured into rectangular shape molds and cured for 48 hours at the room temperature and pressure. Furthermore, a few samples of plain epoxy without nanotubes were also cast for comparison purposes. Dog-bone specimens were tested on a tensile testing machine after different hours of degradation in an environmental chamber. The experimental results showed that the yield stress, ultimate tensile strength and modulus of elasticity gradually reduced over time, indicating that nanocomposites were highly dependent on the humidity and temperature conditions. The results provide a useful guideline for a variety of applications of the nanocomposites in the future.