The use of composites as engineering materials have gained more space in various sectors of human activity. For these materials enable a good synergy between the various components that constitute it, resulting in a range of properties inherent to the material more convenient than the individual components. The strengthening of these composite materials, plant fibers have advantages compared to synthetic fibers because they are abundant, are biodegradable by biological processes, renewable and recyclable. In this paper, polyester matrix composites reinforced by short bamboo fibers arranged randomly were produced, using the lowest possible level of technological processes in production stages. The matrix used was polyester terephthalic pre-accelerated with cobalt naphthenate and cured at room temperature peroxide, methyl ethyl ketone (MEK) in proportion to the resin of 0,33% by volume. The bamboo fibers used were extracted from the campus - Belém of Federal University of Pará. The fibers were manually cut in lengths of 5, 10 and 15 mm, and used without surface treatment and environmental conditions. The composites were made by molding by hand without pressure and room temperature by varying the length of the fibers and different proportions between the components (5 mm - 5,41%) (10 mm - 4,87%) and (15 mm - 3,90%). The fibers were subjected to tensile testing, determination of density and microstructural evaluation by Scanning Electron Microscopy (SEM) of fracture surface. The composites were evaluated in tensile test and evaluation of the fractured surface. Correlating the mechanical properties obtained with the aspect fractographical. The bamboo fibers showed the tensile strength (501,04 MPa) and specific mass (1,35 g/cm₃). The tensile strength of bamboo composites of 5 mm was 17,94 MPa, for bamboo composites of 10 mm to tensile strength was 21,27 MPa for composites and bamboo of 15 mm shear strength was 24,05 MPa. The fracture surfaces were the predominant failure mechanisms for each series of composites manufactured.