Abstract: Flexible valve adpated to have a device inserted therethrough having a body of elastomeric material comprising a cylindrical wall portion with a bore extending therethrough and having a longitudinal central axis. At least three flexible leaflets are provided which adjoin the cylindrical wall portion and subtend 360.degree. of the cylindrical wall portion and are adapted to have said device inserted therethrough. Each leaflet has inwardly inclined planar adjoining first and second wall portions and is vee-shaped in cross-section in a plane perpendicular to the central axis. Each of the first and second wall portions have first and second sealing surfaces at their distal extremities.