One of important mechanical properties of Reinforced or plain concrete with or without silica fume and/or synthetic fibers. In this study the effect of high temperature 600 oC on the compressive strength of reinforced plane concrete containing silica fume and/or synthetic fibers in different percentages as a replacement of Ordinary Portland Cement (O.P.C(is investigated. The percentages of silica fume used were (0%, 2.5%, 5% and 7.5%) and those of synthetic fibers were (0%, 0.2%, 0.4% and 0.6%) of cement weight. The experimental program consisted of testing Fifty-one cube specimen size (150*150*150) mm with targeted 28-day compressive strength of 30 MPa. Forty-five of these specimens, containing silica fume or synthetic fibers or both, were exposed to a temperature of 600 °C for three hours. Six samples were as control specimens, without addition of silica fume or synthetic fibers. Three of these control specimens were exposed to fire. The results showed an increase in the compressive strength was obtained for the specimens with silica fume added and exposed to fire in comparison with the specimens. The highest value of compressive strength was obtained for specimens with (7.5%) silica fume and (0%) synthetic fibers (42 MPa). A lesser increase in the compressive strength was obtained with the addition of synthetic fibers with percentages less than (0.6%), and there is no benefit from adding synthetic fibers with silica fume.