There's an intense growth on the study and development of new materials in recent years, especially in the category of materials that are less harmful to the environment and, moreover, have a low production cost. Following this tendency, composites reinforced with natural fibers that can replace satisfactorily a wide variety of materials have been produced. This work aims to study the properties presented by aplateshaped composite when reinforced by a fiberglass blanket with jute/sisal fibers in different lengths, produced in accordance with ASTM D3039 standard. The composite was produced by hand-lay-up process overlapping jute, sisal and fiberglass layers impregnated with polyester resin, placed in a hydraulic press under a 500 kg load. Specimens in accordance with ASTM D3039 were extracted and tested according to its procedures.