Fully biodegradable, environment friendly 'green' composites were prepared using glutaraldehyde (GA) modified soy protein concentrate (MSPC-G) and flax fabric. Soy protein concentrate (SPC) polymer has low tensile properties, poor moisture resistance and is brittle. SPC polymer with 15% glycerin, as an external plasticizer, exhibited fracture stress and Young's modulus of 17 and 368 Wa, respectively. SPC polymer was cross-linked with GA to increase its tensile properties and improve its processability as a resin to manufacture flax fabric-reinforced composites. GA reacts with the free amine groups in SPC to form crosslinks. MSPC-G showed 20% increase in fracture stress and 35% increase in Young's modulus as well as improved moisture resistance compared to SPC. Besides the mechanical properties, MSPC-G was also characterized for its thermal stability and dynamic mechanical properties. Composite laminates, approximately 1 mm thick, were made using flax fabric and MSPC-G polymer. Composite specimens were prepared with two different orientations, namely, 0 degrees or W. The laminates exhibited a Young's modulus of 1.01 and 1.26 GPa in the longitudinal and transverse directions, respectively. The experimental values were compared with the theoretical predictions using pcGINA (c) software and showed good agreement. The composite specimens also showed good adhesion between flax fabric and MSPC-G resin. (c) 2005 Springer Science + Business Media, Inc.