A passive safety device (20) for a medical needle (21) has a mount (30) for supporting the needle (21) and a needle shielding sleeve (33) co-axial with and arranged for sliding movement relative to the mount (30), from a shielding position to a non-shielding position. An abutment surface is provided on one of the sleeve (33) and mount (30) and is engageable by a radially deformable finger (35), when undeformed. A control member (40) is also slidably arranged with respect to the mount (30) and sleeve (33) and has an initial set position. The control member (40) co-operates with the finger (35) so that on sliding movement of the sleeve (33) from its initial shielding position, the finger (35) is moved radially outwardly, clear of the abutment surface and on to a sliding surface (32). Continued movement of the sleeve (33) increases deformation of the finger (3) and generates a restorative force between the finger and the sliding surface (32) to move the sleeve back to a needle shielding position following the performance of a procedure and return the finger (35) into radial alignment with the abutment surface, the control member (40) remaining displaced from its set position.Linvention concerne un dispositif (20) de sécurité passive destiné à une aiguille médicale (21), comprenant un support (30) servant à porter laiguille (21) et une douille (33) de protection de laiguille qui est coaxiale au support (30) et disposée de façon à coulisser par rapport à celui-ci, dune position de protection à une position sans protection. Une surface dappui est aménagée soit sur la douille (33), soit sur le support (30), et peut être accrochée par un doigt (35) déformable radialement, lorsquil nest pas déformé. Un organe (40) de commande est également disposé de façon à pouvoir coulisser par rapport au support (30) et à la douille (33) et possède une position initiale fixée. Lorgane (40) de commande coopère avec le doigt (35) de telle sorte que, lors du mouvement de translation de la do
