Rubber wood fiber/reinforced thermoplastic natural rubber (RWF/TPNR) composites were prepared. A blend of natural rubber with high-density polyethylene was prepared by melt blending the materials in the internal mixer of Brabender Plasticorder machine. RWF and TPNR were mixed with different fractions of fiber (0, 5, 10, 20, and 30%) in the internal mixer. To investigate the influence of coupling agent on the mechanical properties, concentrations of maleic anhydride polyethylene (MAPE) were employed in the composites. The mechanical properties and morphology of composite material were characterized with tensile machine and scanning electron microscope, respectively. The results showed that the addition of MAPE has a positive effect on the tensile strength and Young's modulus while the maximum strain was reduced. SEM micrographs showed good adhesion between RWF and TPNR when the coupling agent was applied. (C) 2004 Wiley Periodicals, Inc.