Composites with polypropylene (PP) and jute fiber were prepared by injection molding technique. Maleic anhydride-grafted polypropylene was added as coupling agent to improve the adhesion between jute fiber and PP. A high fiber attrition was noted during injection molding, which had negative effects on the mechanical properties of the composites. The coupling agent improved the tensile and bending strengths, however the elastic and bending moduli were found not to be influenced by the coupling agent. The role of the average fiber length in strengthening of the composites was interpreted with help of the critical fiber length. Fracture surfaces of the composites, and the fiber orientations, were investigated by scanning electron microscopy and light microscopy, respectively.