Abstract: A security seal comprises a main body element formed with a passage therein comprising a first portion leading from an entry opening, a second portion leading at an angle from said first portion, and a third portion leading at an angle from said second portion to an outlet opening. One end of an elongate flexible element is fixed to the main body element and the free end of the element is dimensioned to pass into and along said passage. The flexible element is formed along at least a part of its length with apertures adapted to engage with cooperating inclined resiliently flexible projections provided within the second portion of the said passage, the engagement between the projections and apertures being such as to prevent withdrawal of the flexible element from the passage.