A flow regulator for a pump, particularly a vane pump, which regulates the fluid flow delivered to a consumer by the pump, and has a control piston acted on by the pressure built up by the pump, on the one hand, and, on the other, is acted upon by an initial force counteracting this pressure, and has a control edge, which interacts with the discharge bore, and a continuation, which penetrates an aperture, to form a delivery throttle, which is dependent on the piston path. The outside surface (31) of the continuation (25) of the control piston (5) has at least two regions (35, 37) with different outside diameters, separated from one another by a sharp-edged step (39).