Steel-slag asphalt concrete (SSAC) is a type of asphalt mixture that uses slag particles instead of conventional aggregates. It has been proven that replacement of course aggregates by steel-slag particles is the best composition of SSAC mixtures. Despite benefits derived from SSAC, like higher resistance to rutting, the mixture has some disadvantages. Higher optimized asphalt content is the major disadvantage of SSAC compared to ordinary AC mixtures. In order to solve this problem, it is necessary to decrease the bitumen absorption of slag aggregates. One approach that can be taken to increase the viscosity of the bitumen and/or to decrease the effective surface of slag aggregates is reinforcement of asphalt mixtures by using polypropylene (PP) fibers. The main aim of this paper is, therefore, to introduce a novel AC mixture, i.e. PP fiber-reinforced steel-slag asphalt concrete. In this respect, the optimized asphalt content was identified by using Marshall method. Analysis of results shows that the treatment reinforced with 2% of 19 mm PP fibers experiences a decrease in optimized asphalt content about 15% in comparison with the neat mixture, i.e. SSAC sample. Moreover, indirect tensile strength and resilient modulus (M_R) have increased.