The recent improvements of the construction techniques and the particular attention to the environment have renewed the interest in stepped spillways. New experimental investigations have been carried out at the Technical University of Bari, extending the available data on the hydraulic behaviour. The classification of flow regimes has been re-analysed, taking into account the mathematical relationships derived from the technical literature. The study confirms the difficulties in understanding the problem and points out the need for standard experimental procedures, for refining the hydraulic comprehension of the problem.