Cantilever beams are widely used in reinforced concrete structures. Due to deflections in a cantilever, cracks occur. The formation of a crack is unfavourable and decreases the bearing capacity of a reinforced concrete member. The use of steel fiber in reinforced concrete is widespread, since it prevents the formation of cracks and increases ductility. The significance of this study is an experimental report of the use of steel fibers in a reinforced concrete cantilever beam, and their contribution to its behaviour. Therefore, reinforced concrete cantilever beam samples, with and without steel fiber additions, were produced. As cyclic loads were applied, the behaviour of the samples was examined. As a result of the study, it is experimentally found that by addition of steel fibers into reinforced concrete cantilever beams, crack widths decrease and their ductility increases. Stiffness decreased less in reinforced concrete cantilever beams with steel fiber addition, and, thus, it was concluded that use of steel fibers is favourable for their behaviour. (C) 2014 Sharif University of Technology. All rights reserved.