Abstract: The effects of some animal materials, viz feather, hide and hoof, as fillers for polystyrene were investigated. Composites of varying weight percentages of fillers in fixed weight of the polymer resins were produced for each filler type by the injection moulding technique. The physico-mechanical and thermal properties of the composites prepared showed variations in the properties such as, tensile strength, elongation at break, compressive strength, flexural strength, surface hardness and melting and crystallization temperatures. These materials of animal origin can be used as fillers and mainly as biodegradable fillers for polymer resins and form bio-plastics.