The concrete, as material commonly used in construction, has been the subject of research for many years in order to improve the properties. One way to improve is to use the steel fibers. In the paper a comparative analysis of selected mechanical properties for concrete and fiber-reinforced concrete, e.g. compressive strength and Young's modulus, was presented. It was checked how the value of Young's modulus and the compressive strength of concrete change depending on the content of steel fibers. Three types of samples were prepared and tested: 1 -concrete, 2-fiber-reinforced concrete containing 0.25% of steel fibers, 3-fiber-reinforced concrete containing 0.50% of steel fibers. The conducted research was to show composition of which sample is the most advantageous and how many fibers should be used to obtain the mechanical properties, in this case compressive strength and Young's modulus, the best. The research covered the preparation of concrete samples, their curing and seasoning, measurements of Young's modulus and compressive strength with the use of a strength press, as well as the analysis and interpretation of the obtained results. As the analysis has shown, the greater number of steel fibers is not directly proportional to the increase in its compressive strength or the value of Young's modulus.