The protector (1) for an injection needle (2), comprising a support (3) and a sliding sleeve (4) with its distal end (15) designed to make contact with the injected surface as it is moved axially by a spring (14), has axial guides (29, 30) for the sleeve to prevent it from pivoting as it moves axially, and at least one lug (6) on the support or sleeve that engages with a slot (10) in the other component. The slot has a basic U-shaped configuration, with one section (11) followed by the lug as it moves from its storage to its injection position, and a second section (12) that the lug follows as it moves from its injection to protection position. Between the two sections the central portion of the U is a flexible projection that prevents the lug from returning along the wrong section, while the lug moves on flexible arm (5).
