Abstract: The invention relates to a valve, comprising a valve body for controlling a medium flowing through the valve, a valve housing (3), in which the valve body (1), which has at least one gasket (4) for sealing cooperation with the valve housing (3) or where appropriate with a cage (5) arranged in the valve housing, is axially displaceable by a spindle (6) in the direction towards and from a valve seating (7) in the valve. The gasket (4) extends peripherally around the circumference of the valve body (1) and is expandable in the radial direction to tight abutment against the valve housing (3) or the cage (5) arranged in the latter through axial pressing of at least one press member (9′) acting on the gasket (4) when the valve body (1) is just before and/or in its closing position.