Abstract: A security closure device for a bottle, which is intended to prevent the fraudulant refilling of a bottle is disclosed. The bottle closure device disclosed has an internal valve which is held shut when the device is in a normal upright position by the weight of a ball which is trapped in a valve chamber between the valve shutter and a plurality of inclined radial ribs. The inclination of the radial ribs is such that when the bottle closure device is held with its axis horizontal the ball rolls down those of the ribs which are lowermost at the time and into engagement with the valve shutter to hold this shut against the valve seat. In order to open the valve it is necessary to tilt the bottle closure device to a position past the horizontal where the ball can roll along the edges of those of the radial ribs which are lowermost at the time to release the valve shutter and allow liquid to flow from the bottle.