This article deals with experimental and numerical investigation of flow in an axial turbine stage with prismatic blades which are not equipped with the shroud.Main attention is paid to explain the influence of the radial clearance under the stator blade on the flow around the rotor blade.The experiment was performed on the test rig equipped with the water brake dynamometer, torque meter and rotatable stator together with the linear probe manipulator.Numerical modelling was carried out for the unsteady flow using the ``sliding mesh'' interface between the stator and rotor wheels.Results of the numerical simulation are compared with the experimental data.