A protective device for a syringe needle comprising an elastic cap (20) having a closed distal end (24) and an open proximal end (22), said cap (20) delimiting an inner housing (26) intended to receive the distal portion (104) of the body (102) of a needle syringe (100), an end wall (30) of said cap (20) being able to be pierced through a part of its thickness by the free end of said needle (106), said housing (26) comprising, from said proximal end (22), a first frustoconical or cylindrical section (40), a second cylindrical section (42) having a diameter (D2) smaller than the maximum diameter (D1) and intended to house the distal portion (104) of the syringe body (102) that carries said needle (106), a third section (44) that tapers from said second section (42) towards the bottom (38) of said housing (26), said side wall (28) being further provided with an annular bead (70) disposed in said housing (26) between said first and second sections (40, 42) of said housing (26), at least one slot (72) extending in a longitudinal direction on said annular bead (70), in which said second section (42) comprises at least one annular groove (420) extending longitudinally over a part of the height of said second section (42).Dispositif de protection pour aiguille de seringue comportant un capuchon (20) élastique possédant une extrémité distale (24) fermée et une extrémité proximale (22) ouverte, ledit capuchon (20) délimitant un logement interne (26) destiné à recevoir la portion distale (104) du corps (102) dune seringue à aiguille (100), une paroi dextrémité (30) dudit capuchon (20) étant susceptible dêtre percée sur une partie de son épaisseur par lextrémité libre de ladite aiguille (106), ledit logement (26) comprenant, depuis ladite extrémité proximale (22) un premier tronçon (40) de forme tronconique ou cylindrique, un deuxième tronçon (42) cylindrique présentant un diamètre (D2) inférieur au diamètre maximal (D1 ) et destiné à loger la portion distale (104) du corps de
