Unregenerated-cellulose-fiber-elastomer composites with widely varying properties can be obtained. The properties depend on the type of elastomer used as the matrix, the fiber concentration, fiber aspect ratio, and fiber orientation. The fibers must be bonded to the matrix elastomer to obtain good strength. Composites of good strength can be prepared from a wide variety of elastomers. Composites with Young's modulus from 20000 to over 100000 psi and strengths up to 6000 psi can be obtained by varying the amounts or lengths of fibers. In addition, these compositions offer a high degree of dimensional stability; they resist creep deformation and solvent swelling. Further, compositions of good fatigue life under high stress conditions can be obtained. It is expected that the new composite compositions will find uses where good long-term load-bearing characteristics and dimensional stability are required. Uses in a number of environments are indicated since a wide variety of elastomers can be used as matrix.