Novel "green composites" have been prepared using a conjugated soybean oil-based resin and corn stover as a natural fiber. Corn stover is the residue remaining after grain harvest and it is estimated that approximately 75 million tons are available annually in the United States. The effect of the amount of filler, the length of the fiber, and the amount of the crosslinker on the structure and thermal and mechanical properties of the composites has been determined using Soxhlet extraction analysis, thermogravimetric analysis, dynamic mechanical analysis, and tensile testing. Increasing the amount of corn stover and decreasing the length of the fiber results in significant improvements in the mechanical properties of the composites. The Young's moduli and tensile strengths of the composites prepared range from 291 to 1398 MPa and 2.7 to 7.4 MPa, respectively. Water uptake data indicate that increasing the amount and fiber length of the corn stover results in significant increases in the absorption of water by the composites. The composites, containing 20 to 80 wt.% corn stover and a resin composed of 50 wt.% natural oil, contain 60 to 90 wt.% renewable materials and should find applications in the construction, automotive, and furniture industries. (C) 2010 Elsevier Ltd. All rights reserved.