The curauá fiber, a bromeliad (Ananas erectifolius LB Smith), is considered large in the Amazon region, its mechanical properties of high strength, low density - capable of giving lightness to the final product - and potential for recycling, is listed for replace the fiberglass used as reinforcement to the plastic in the manufacture of parts with reduced features and detailed, produced by injection molding process, such as cars panel buttons, knobs and hinges. The materials used for manufacturing the polymer composites were curauá fibers acquired commercially from Belém in nature form, and a matrix of polyester resin terephtholic unsaturated and pre-accelerated chosen from one of the proportions of 0.33% (v / v), 1.66% (v / v), 3.33% (v / v) and 5% (v / v) which was initially studied. In the manufacture of the composite resin was used in combination with curauá fibers with lengths of 10 mm and a mass fraction of 3.87%, 4.87% and 5.87%. The tensile strength of the curauá composites of 10 mm with mass fraction of 3.87% was 23:22 MPa, for composites with mass fraction of 4.87% was 25.12 MPa, and for composites of mass fraction of 5.87% was 29.21 MPa. The mechanical properties were evaluated by tensile test and the surfaces generated were evaluated by scanning electron microscopy in order to correlate aspects of fracture with its mechanical properties. In which the fracture surfaces showed some dominant failure mechanisms such as pull out (tearing of the fibers) and detachment of the fiber matrix.