The invention relates to a pressure regulating valve comprising a valve body having one or more inlet openings and one or more outlet openings for a pressurized medium, an internal cavity connecting said inlet and outlet openings and a piston which is in contact with a valve seat between inlet and outlet and is axially slidable in the cavity in the valve body against a spring, which biases the piston to a closed position, whereby the valve opens when a predetermined pressure acts on the piston. The valve body is provided with an opening at its outlet side, where the cross-section of the opening is smaller that the cross-section of the cavity and which opening is in connection with a volume limited by the piston and the lower section of the internal cavity, whereby the pressure drop across the valve dampens variations in the volume.