A needle shroud assembly (10) comprises a barrel (16), a needle shroud (18) captively telescoped relative to the forward end of the barrel for movement between retracted and extended positions and is biased towards said extended position by a spring (25). A separate locking element (42) is mounted within the barrel moveable between a safe position (as seen in FIG. 5) in which it prevents or limits retraction movement of said needle shroud (18), and a live position in which it is clear of the rearward path of the needle shroud (18). The locking member is moved from its safe position to its live position by means of an externally operable actuating member (54), having a cam (52) which cooperates with a cam surface (46) on the locking element (42). The cam (52) is driven back to its original position by the rearward end of the shroud (18) as it moves to the fully retracted position.