Lignocellulosic fibers are obtained from agriculture (60%) and forests (40%) industry. Tropical countries produce high amount of these fibers as a by-product. The use of natural fibers is interesting due to their biodegradation capabilities as well as their damping properties, low density and moderate strength. Hence, in the present chapter, the facts due to which natural fibers can be used as reinforced polymers along with the importance and role of the interfacial region will be discussed. In addition, the effect of incorporating chopped natural fibers of different length, as disperse reinforced phase, on the dynamic or quasi-static elastic modulus of glass fiber laminates will be analyzed. A glass fiber composite material model used as a coir fiber effect test bed and a simple, easy and sensitive cantilever experimental setup were validated which are presented with comparative results.