The natural fibers presents an intense target of research by the scientific community, they're an interesting option of reinforcement for polymeric matrix composites, due to their good properties of tensile resistance and flexibility; also, their low cost, easy accessibility and biodegradable characteristic, motivates studies about their applicability on industry and materials science. The objective of this study is to manufacture plates shaped polyester matrix composite, reinforced by jute fiber and fiberglass blanket for tensile test. Results and discussion about the properties the reinforcements attributed for the composite are compared to others composite materials. The fibers were cut in length of 10 mm and 50 mm, and blankets of random organization were made of them. They were used as the only reinforce of the plate, or together with fiberglass blankets. The blankets were impregnated with polyester resin and put under a 5kN load, creating a plate where were extracted specimens in the ASTM D3039. The results shows that the length of the fibers contributes for the composite strength, the longer the fibers are the higher is the tensile resistance, corresponding to 11.05 MPa for 10 mm length and 17.32 for 50mm length. The hybrid plates reinforced with jute and natural fibers showed gains on tension in every length condition, corresponding to 27.73 MPa for 10mm and 31.51 MPa for 50 mm.