Wood flour (WF)-polycaprolactone (PCL) and polybutylenesuccinate-butylenecarbonate (PBSC) composites were prepared by knead processing. The effects of a compatibilizer on the tensile and thermal flow properties of the composites were investigated. PCL-graft-maleic anhydride (PCL-g-MA) was used as a compatibilizer. Tensile properties were improved by adding PCL-g-MA to both composites. The tensile strength and Young's modulus were increased from 13 to 27 MPa and 581 to 1011 MPa in WF-PCL (50/50, w/w) composites, respectively, and from 17 to 28 MPa and 814 to 1007 Mpa in WF-PBSC (50/50, w/w) composites, respectively, with the addition of 5% PCL-g-MA. Elongation at break increased from 4 to 7% and from 3 to 6% in the WF-PCL and the WF-PBSC composites, respectively. Tensile strength was further increased with increasing WF content in the presence of PCL-g-MA. Thermal flow temperature and melt viscosity of the composites were increased, and water absorption and thickness swelling were improved with the addition of PCL-g-MA. It was found from the burial test that all composites were more than 40% degraded within 6 weeks, and there was no considerable difference in degradation between composites with PCL-g-MA and those without. (C) 2003 Wiley Periodicals, Inc.