A cover (40) for a tip (42) of a medical device such as a needle (41) is disclosed. The medical device has a body from which there extends an elongated part (41) terminating at said tip (42). The cover includes a cover body (43), and an elongated flexible element (47). The cover body can be mounted on the elongated part (45) for sliding movement along the elongated part, from a retracted position at which the cover body is spaced from the tip (42), to an extended position where the tip (42) is located within and covered by the cover body (43). The elongated flexible element (47) is attached to the cover body (43) and used by an operator so that when tensioning the element the cover body is moved from the retracted position to the extended position where flexible element (47) is released from engagement with said cover body when said tip (42) is located internally of said cover body (43).
