This article presents the results of a study of the processing and physicomechanical properties of environmentally friendly wood-fiber-reinforced poly(lactic acid) composites that were produced with a microcompounding molding system. Wood-fiber-reinforced polypropylene composites were also processed under similar conditions and were compared to wood-fiber-reinforced poly(lactic acid) composites. The mechanical, thermomechanical, and morphological properties of these composites were studied. In terms of the mechanical properties, the wood-fiber-reinforced poly(lactic acid) composites were comparable to conventional polypropylene-based thermoplastic composites. The mechanical properties of the wood-fiber-reinforced poly(lactic acid) composites were significantly higher than those of the virgin resin. The flexural modulus (8.9 GPa) of the wood-fiber-reinforced poly(lactic acid) composite (30 wt % fiber) was comparable to that of traditional (i.e., wood-fiber-reinforced polypropylene) composites (3.4 GPa). The incorporation of the wood fibers into poly(lactic acid) resulted in a considerable increase in the storage modulus (stiffness) of the resin. The addition of the maleated polypropylene coupling agent improved the mechanical properties of the composites. Microstructure studies using scanning electron microscopy indicated significant interfacial bonding between the matrix and the wood fibers. The specific performance evidenced by the wood-fiber-reinforced poly(lactic acid) composites may hint at potential applications in, for example, the automotive and packaging industries. (c) 2006 Wiley Periodicals, Inc.