Abstract: Sealing means for a sliding gate valve with a frame having a bottom frame member, a top frame member with an aperture therein generally transverse to the direction of fluid flow through the valve, and parallel, rectilinear side frame members and a gate having parallel, rectilinear sides adapted for sliding movement through the aperture to a closed position within the frame to restrict the flow of fluid through the frame. The seal is effected by a flange that is fixedly mounted on at least one frame member downstream of the aperture and in the interior of the frame and is parallel to the gate, and a longitudinal strip of resilient material fixedly mounted on at least one side frame member in the interior of the frame and in the plane of the gate. The flange is adapted to contact the downstream surface of the gate and limit the gate's downstream displacement due to the pressure of fluid when it is in the closed position and subjected to fluid pressure against its upstream surface.