This invention concerns a valve (20) for respiratory masks. The valve (20) comprises a valve body (26) shaped to define a valve opening (30), and a valve member (22) which is mounted to the valve body (26) such that the valve member (22) is actuable between open and closed conditions relative to the valve body (26) in response to a pressure differential across the valve (20). The valve member (22) comprises first and second portions (22A,22B) arranged for contact with the valve body (26) in the closed condition and the valve member (22) is pivotably mounted such that the first and second portions (22A,22B) of the valve member (22) are actuated into the open condition in opposing directions relative to the valve body (26).
