Abstract: A security device for a slide fastener, including a housing adapted to be fitted to an object to which the slide fastener is attached, the housing substantially surrounding the slider of the slide fastener in its fully closed position, a closure member adapted to cooperate with the housing which, in use, covers the slider to prevent access thereto and a frangible locking element adapted to link the housing to the closure member, the locking element being resiliently yieldable and slidably insertable into the closure member but not retractable therefrom without fracturing the frangible locking element. The closure member is attached at one end to a puller and the puller is attached to the slider. In a preferred embodiment the closure member can pivot about the housing and block withdrawal of the slider from the housing in its closed position.