Protection for the otherwise exposed sharp point of a needle of an injection device. A two part cover for the needle comprises a stationary base which engages the injection device, and a relatively movable cover. The cover is guided to slide longitudinally along the base by a groove-and-projection system. The projection is held in an initial position, and slides along the groove during injection. At the end of the injection, the projection is immobilized in the groove at a final position, and immobilizes the moveable cover in a deployed position covering the needle.
