The objective of this study was to investigate dimensional stability and mechanical performance of Paulownia elongate wood flour filled polypropylene composites with and without maleic anhydride-grafted polypropylene (MAPP) at 30, 40, 50, and 60 wt% contents of the wood flour. The thickness swelling and water absorption of the specimens increased with increasing wood content but these increments were significantly lower than thermoplastic composites filled with other fast growing woods such as eucalyptus and poplar. The modulus of elasticity in bending and tensile of the polypropylene composites improved with increasing the wood flour content while the bending, tensile, and impact strengths decreased. Adding the MAPP (3 wt%) significantly improved the dimensional stability and mechanical properties of the composites. All WPC types had a higher melting temperature compared to neat polypropylene. Thermal stability of the polypropylene increased with increasing wood flour content. The test results showed that P. elongata wood is an efficient reinforcing filler for thermoplastic composites in applications requiring high dimensional stability. (C) 2012 Elsevier B.V. All rights reserved.