This paper presents results of an experimental investigation carried out on high strength fibre reinforced concrete beams in the presence of traditional steel reinforcement, subjected to monotonic and cyclic loads. The aim of the investigation was to point out the effectiveness of the fibres as shear reinforcement of the beams, and to show the possibility of changing the shear mode of failure, characterised by high brittleness and poor dissipative capacities, into a flexural mode of failure, which is certainly more suitable in structures designed in seismic areas.