The mechanical response of bamboo fibers to variation in moisture content (MC) has a direct influence on the performance of bamboo fiber-based products, both during their processing and final practical applications. However, due to the experimental difficulties involved in testing, this fundamental process remains poorly understood. In this paper, longitudinal tensile modulus (TE), ultimate tensile strength (UTS) and elongation at break (EB) for four different MC levels, ranging from approximately 4.97 to 26.2 %, were determined for single bamboo fibers aged 0.5, 1.5 and 2.5 years old, respectively. For each MC level, the results show that both TE and UTS of bamboo fibers vary little with age. A general linear reduction is observed for both TE and UTS when MC increases, while EB shows a slight increase. Furthermore, TE is found to be most sensitive to MC change, followed by UTS and then EB. A close examination revealed that 2.5-year-old bamboo fibers are more sensitive to MC change than younger specimens, which may partly be related to their relatively higher microfibrillar angel (MFA). A direct TE-MC plot comparison between bamboo fibers and solid bamboo not only demonstrates the decisive role of the fiber component in the overall mechanical response to MC of bamboo, but also reveals that the TE of the former is less sensitive to varying MC levels than the latter.