High- density polyethylene (HDPE) in used plastic bags was reinforced with chicken feathers to develop composites in an effort to add value and reduce the amount of the plastics and feathers disposed in landfills. Feathers are biodegradable, derived from renewable resource, and are inexpensive and HDPE in plastic bags is mostly discarded in landfills. Utilizing feathers as reinforcement for HDPE composites will provide an opportunity to develop environmentally friendly composites. In this research, HDPE plastic bags were reinforced with chicken feathers and the flexural, tensile and acoustic properties were studied. It was found that incorporating feathers substantially improved the flexural properties and tensile modulus. At the optimum condition, the HDPE-feather (50/50) composites had flexural strength of 13.9 MPa and stiffness of 0.45 N/mm compared to 9.8 MPa and 0.29 N/mm for 100% HDPE. The 50/50 HDPE-feather composite had similar tensile strength but more than twice the tensile modulus of neat HDPE. (c) 2013 Wiley Periodicals, Inc.