In this work, composites of polystyrene reinforced with various amounts of sheep's wool ranging from 5 to 10 wt% were prepared by hot compresion molding. Wool fibers and polystyrene pellets were placed in a rectangular mold of a thickness of 3.2 mm and compressed at a temperature above softening temperaturte of Polystyrene. The material was removed from the mold and then cut into bars in accordance with ASTM D256 for Izod impact strength test.It was shown that one may tremendously increase, by more than three folds, the toughness of a brittle ploymer such as Polystyrene by incorporating long fibers of natural wool (sheep's wool).