Mechanical behavior of composites depends on the individual properties of each component; however, bonding between fibers and matrix plays a predominant role in the material performance. The interfacial region, which is considered as a zone of property gradients, determines the stress transfer between the bonded fibers and the matrix. A well establish interface linkage assures an adequate mechanical behavior of composite materials.The main disadvantage for using natural fibers as reinforcement of polymeric matrices is the physicochemical incompatibility between fibers and matrix. Because of the hydrophilic nature of fibers and the hydrophobic character of resins, it is necessary to treat both materials in order to improve the final properties of composites, avoiding premature and delamination failures.This paper describes an exploratory research intended to use Guadua angustifolia bamboo fibers as reinforcement of polymeric matrices. Two different techniques of compatibilization were employed: first, standard baths of sodium hydroxide as coupling agent were applied to fibers, and second, a novel plasma treatment was implemented for natural fibers. The influence of both compatibilization methods on tensile strength and surface appearance of fibers were evaluated. Results confirm that sodium hydroxide baths decrease the mechanical strength of fibers and clean its surface. In contrast, plasma treatments showed very encouraging results, without changes on mechanical strength and improving the fiber surface.