Abstract: A valve, of the type employing a plug rotatable through substantially 90.degree. between open and closed valve positions, employs a plug which has an elongated configuration along its axis of rotation with the opposing ends of said elongated plug each exhibiting a spherical, ellipsoidal, or other curved configuration that merges smoothly into the elongated sides of the plug. The plug is provided with a passageway which is elongated in the direction of elongation of the plug and which extends through the plug in a direction transverse to the axis of rotation of the plug. The plug surface is sealed relative to the valve housing by at least one continuous seat of elongated closed loop configuration which engages the surface of the plug along a continuous noncircular line or band having a direction of elongation extending generally in the same direction as the central axis of the plug.