DOI: 10.7764/RDLC.18.2.386Behaviour of construction materials i.e. steel, concrete and mortar under elevated temperature is important. In the study, the variations in mass loss, and strengths of polypropylene fiber reinforced mortar subjected to elevated temperatures were examined. Mortar was made with CEM I 42.5R Portland cement, monofilament polypropylene fiber, fine aggregate and drinkable water. The sand-cement and water-cement ratio were chosen 3:1 and 1:2 for all mixtures, respectively. Mixes containing 0, 0.1, 0.2 and 0.3% polypropylene fiber in volume of solid matter of mixture were prepared. Mortars were exposed to 100, 200, 400, 600 and 800°C temperatures and cooled down 23±2°C in air and water. There was a difference between the temperatures at which the important reductions observed for flexural tensile and compressive strength. Significant reduction was observed at 400°C for compressive strength and while it was 200°C for flexural strength. No difference was observed between air cooling and water cooling regimes up to 600°C; however, at 800°C the residual compressive and flexural strength of water cooled mortar was about 40% of the air cooled mortar. Mortar containing polypropylene fiber presented better behaviour to elevated temperature in terms of relative residual strengths up to 400°C.