The performance of asphalt roads is affected by many factors such as temperature, water, loads and materials characteristics. These factors cause thermal cracking, permanent deformation (rutting) and fatigue distresses on asphalt concrete layers. In the last years, many researchers studied improving the performance of asphalt concrete by using polypropylene synthetic fibers (PPF). This paper describes a laboratory study on the mechanical characteristics of asphalt mixtures by reinforcing them with polypropylene fibers and improving their characteristics and durability. The physical characteristics of the asphalt binder (Penetration at 25°C, ductility, softening point) were carried out on reinforced and unreinforced asphalt binders with polypropylene fibers. It was found that the PPF reinforced asphalt can improve the consistency and characteristics of asphalt concrete. Asphalt concrete specimens were prepared with varying contents of polypropylene fibers (0%, 3%, 4%, 5% and 6% by weight of asphalt binder). In total, sixty specimens were prepared by using Marshall Mix design method (fifteen specimens were used to determine the optimum asphalt binder content and the remaining specimens were used to investigate the effect of reinforcing the asphalt mixtures with PPF. The mechanical characteristics of the reinforced asphalt mixtures with polypropylene fibers were compared with a reference asphalt mixture. The results show that increasing the amount of PPF in the asphalt mixtures led to increases in Marshall Stability and air void in the total mix, while the flow values decreased for all mixtures. It is noticed that the use of 5% PPF shows the highest stability value with flow and air voids values within specification limits [ASTM].