In this study bio-nanocomposites were manufactured, using a thermoset resin based on lactic acid and nanoclay (montmorillonite) as a matrix for flax fibers. The obtained composites were characterized by dynamic-mechanical thermal analysis (DMTA) and flexural testing. The aim of this study was to evaluate the mechanical properties of bio-nanocomposites without any surface treatment of the nanoclay and to use the resin/clay blend as a matrix for natural fiber composite. Results showed the nanoclay improved the mechanical properties.