Abstract: A mechanically actuated pinch valve for high pressure use which opens to a full round configuration and which closes to a leak tight locked condition. A novel valve actuating mechanism permits the full closure of the valve even with working pressures in the range of 400 psig by a relatively small rotary closing force acting through a 90.degree. arc. A linkage within the valve housing provides a decreasing pinch bar movement with increased actuator rotation so that the maximum mechanical advantage is achieved at the point of valve closure. The thrust of the line pressure, which may be carried on either side of the valve, is borne by bearings at the ends of the pinch bars which ride in grooves in the housing. The actuator automatically locks in the closed position regardless of the direction of the line pressure.