This paper investigates how polypropylene fibres modify the mechanical properties of concrete using crushed stone (dolomite) as the coarse aggregate under elevated temperatures. For this purpose, the experimental study, concrete specimens were tested. These specimens were subjected to three different temperatures and three different duration times. Cubes, and cylinders were chosen as the test specimens. Two concrete mixes were prepared, one mix without polypropylene fibres and the other mix with 0.21% or 1 kg/m3 of polypropylene fibres. Specimens were exposed to different temperatures, 25 °C (normal conditions), 200 °C, 400 °C and 600 °C and different exposure times, 30, 45, and 60 minutes. The following mechanical properties were investigated: tensile strength, compressive strength, and modulus of elasticity. From the experimental results, incorporating polypropylene fibres slightly improved the mechanical properties of concrete at room temperature. At elevated temperatures, the use of polypropylene fibres minimized the reduction in mechanical properties up to 400 °C.   However, the use of polypropylene fibre had no influence on the concrete mechanical properties at temperatures greater than 400 °C for 60 min. The worst mechanical properties were observed at temperatures greater than 400 °C. The mechanical properties of non-fibrous concrete decreased gradually at 400 °C and decreased dramatically at 600 °C.