The invention relates to an anti-syphon valve for controlling the flow of fluid therethrough. The anti-syphon valve includes a body which has an inlet and an outlet, and a valve member which is retained within the body. The valve member is movable between a first configuration in which the valve member restricts fluid communication between the inlet and the outlet, and a second configuration in which the valve member permits fluid communication between the inlet and the outlet. The valve member is provided with a stabiliser which stabilises movement of the valve member.