Abstract: The sealing element of a butterfly valve includes a rigid support ring, and an elastically yieldable sealing ring which partially embeds the support ring within itself. The sealing ring has an inner portion which is juxtaposed with the inner periphery of the support ring, and two end portions which emerge with the inner portion and extend therefrom in the radially outward direction in juxtaposition with respective axial end faces of the support ring. At least one of the end portions of the sealing ring terminates before it reaches the outer peripheral surface of the support ring, so that it exposes an annular zone of one of the axial end faces of the support ring. An annular, circumferentially complete, projection of the valve body extends into the passage at the downstream end thereof as considered in the direction of fluid flow through the passage in the fully open position of the valve member.