A valve for controlling the flow of a fluid, in particular a liquid, said valve comprising a closure member (1) of compact shape which is resiliently deformable, at least superficially, and which is suitable for closing or exposing a fluid flow orifice (2) which opens out at a surface (3) of the valve body (4), the surface (3) of the valve body (4) is generally plane and the closure member (1) is mounted to rotate freely about an axis (5), on support means (6) which are constructed so that, when the valve is closed, the closure member (1) approaches the orifice (2) with zero or a relatively small incidence with respect to the plane surface (3) so that, at least at the end of the approach, the closure member (1) rolls on the plane surface (3) and is resiliently compressed against that surface until it covers the orifice (2) which it then closes sealingly, the support means also being constructed so that, when the valve is open, the closure member (1) is held away from the orifice (2) and is not compressed against the surface (3).