Abstract: A hydrodynamic shaft seal includes a sealing element defined by two radially extending faces, with concentric annular inner and outer edges forming the boundaries of the faces. The element includes a radially outwardly extending fixed body portion and a radially inwardly extending flexible body portion, a flexure ring defined by the boundary between the latter body portions. The faces of the element have a continuous divergence from the outer edge to the inner edge, the divergence falling within the range of 0.006 to 0.060 inch per inch of radial length of the flexible portion. The divergence results in an increasing lateral separation of the faces from the outer edge to the inner edge. In a preferred embodiment, the element has a wall thickness in the range of 0.025 to 0.050 inch, and the flexible body portion thereof has a radial length in the range of 0.200 to 0.600 inch.