Generations of plastic wastes are increasing in alarming rate in recent years and became series environmental problems for both developed and developing countries. The best way to deal with these wastes is to recycle and reuse them as raw materials or modifiers. This will reduce the consumption of virgin raw materials especially, non renewable resource, and it will reduce the spaces used for landfills. Utilization of waste low density polyethylene (LDPE) in asphalt mix is found to improve the performance of asphalt roads and reduce pollution problems. This study was intended to investigate the effect of using shredded waste LDPE plastic as a modifier of virgin bitumen, to investigate the optimum allowable percentage of waste LDPE plastic content, to evaluate the rheological properties of waste LDPE modified bitumen and to evaluate the Marshal properties of waste LDPE modified asphalt mixes. Waste low density polyethylene plastic mixed with pure bitumen using wet blending method. Four modified bitumen mixes prepared with 4%, 6%, 8% and 10% waste plastic content by the weight of optimum bitumen content (OBC) at different mixing temperatures (160oC, 170oC and 180oC ) and different mixing times (1 hour, 1.5 hour and 2 hour ) to evaluate penetration point, softening point and ductility. Results indicated that penetration point and ductility value of plastic modified bitumen were reduced while softening point of plastic modified bitumen was higher compared to non modified bitumen. 170oC mixing temperature and 1.5 hour mixing time results, homogeneous mix between bitumen and waste LDPE plastic materials compared to other mixing temperatures and mixing times. Marshall Test Method was used to determine the optimum bitumen content and to evaluate the marshal properties of the plastic modified asphalt mix. In total, 33 marshal samples were prepared to determine the optimum bitumen content and the optimum plastic modified bitumen content. The OBC of non modified marshal sample was found to be 5.16% by weight of the total aggregate while the optimum waste LDPE modified bitumen content was found to be 6.5% by weight of the OBC. Asphalt mix modified with 6.5% of waste LDPE plastic content has 33.67% higher stability value compared to the non modified asphalt mix. Plastic modified asphalt mix exhibit lower bulk density, lower flow, higher air voids, higher voids filled with aggregate and lower voids filled with bitumen.