Fibers stripped of from the bamboo culm by longitudinal cutting are being considered as reinforcement of polymer composites owing to environmental benefits related to their biodegradable and renewable characteristics. The manual cutting process allows bamboo fibers with different diameters to be extracted from the culm. Since a lignocellulosic fiber usually presents tensile strength dependence with its diameter, this possibility was investigated on bamboo fibers by means of the Weibull statistical analysis. It was found that the smaller the fiber diameter, the greater the tensile strength. Fracture observation of ruptured bamboo fibers by scanning electron microscopy, identified possible mechanisms associated with this inverse strength/diameter correlation.