This work was devoted to study the potential of different agro-wastes as reinforcements for thermoplastics as an alternative to wood fibers. Thermal degradation characteristics of the fibers were studied to investigate the feasibility of these fibers to the processing point of view. The effects of fiber loading on the mechanical properties, as well as crystallization, melting behavior and viscoelatic behavior were also studied. Special attention was made for the fibers particle size; most fibers were ground by a rotor mill. In order to reduce more the average size and the size distribution of fiber particles, a process with ionic liquid was used for dissolution and regeneration of the agro-waste fibers. Bio-composites were prepared by combining 40% of agro-wastes with polylactic acid (PLA) using HAAKE MiniLab twin-screw micro compounder. In general, the agro-wastes showed a good potential to be used as a filler in production of bio-composites.