A sliding valve including a valve body (1) with a wall having a valve opening (3) and a valve seat (4) surrounding the valve opening (3), a valve plate (5), at least one valve rod (8) that can move in the axial direction and can be moved for closing the valve starting from a first position in which the valve plate (5) assumes its open position, to a second position in which the valve plate (5) assumes an intermediate position covering the valve opening (3) but lifted from the valve seat (4), into a third position in which the valve plate (5) assumes its closed position. At least one lifting element (10, 11) moves the valve plate (5) from its intermediate position into its closed position, and at least one support unit (12) with at least one front and at least one rear support element (14, 13) that interact in the closed position of the valve plate (5) with at least one valve-body-fixed, front support element and at least one valve-body-fixed, rear support element (16, 15). In the second position of the valve rod (8), either the rear support elements (13, 15) or the front support elements (14, 16) are in engagement and the other of these support elements (14, 16; 13, 15) are spaced apart from each other. When moving the valve rod (8) from its second to its third position, the support unit (12) pivots about a rotational axis (17) from a starting position in which the other support elements (14, 16; 13, 15) are spaced apart from each other into an end position in which the other support elements (14, 16; 13, 15) contact each other.