This study concerns the preparation of eco-composites based on natural fibers coming from wood and subproducts (rice husks) and products (kenaf) of annually grown plants. The matrices used were of two types: a biopolymer (PLA) and a petroleum-derived polymer (HDPE). Results showed that natural fibers markedly increase the tensile and flexural properties of both polymers by extending the field of application of these materials with less use of nonrenewable resources. The properties obtained are comparable to commercially available fiber-filled composites. Moreover, processing can easily be carried out in one step below a critical fiber volume. Fire and durability performance of the composites can be also improved by adding typical fire retardants and pigments. (c) 2007 Wiley Periodicals, Inc.