. The research is studying the use of domestically produced steel fibers, as an ingredient in the manufacture of reactive powder concrete (RPC), in order to reduce dependence on imported steel fiber used in the manufacture of RPC. The volume of steel fibers used in this study was 0.0%, 1.0%, 1.5% and 2.0%, while the ratio between the length of the fiber to its diameter, or was designated aspect ratio (l / d) of each is 50, 75 and 100. Test specimen in the form of a cylinder with a diameter of 75.0 mm, 150.0 mm length, the beam size 100,0 mm 100,0 mm x 350.0 mm. the curing process the specimen is immersed in water for 3 days at 20oC followed by steam curing at 90°C for 8 hours. The specimen was tested on the compressive strength and flexural strength (modulus of rupture) of concrete after 28 days old. The results of the research, 0.3 mm fiber diameter decreases the compressive strength of RPC, otherwise increasing the flexural strength of RPC in the amount of 300% - 400%. Optimum value of compressive strength and flexural strength in 1.5% of fibre volume and aspect ratio l / d = 75 with the value of 89.36 MPa and 27.01 MPa.