Dispensing assembly having a syringe (100) comprising a body (102) provided with a ball (104) supporting a needle (A) provided with a tip (P), and a removable guard (10) for a syringe needle, said guard (10) having an elastic cap (20) which defines an inner cavity (26) delimited by a lateral wall (28) and by a distal end wall (30), said end wall (30) being solid and receiving said tip (P) of said needle (A) of a syringe (100) in a leaktight manner in the protection position, said lateral wall (28) having an annular bead (70) provided with at least one slit (72) extending in the longitudinal direction on said annular bead (70), said annular bead (70) cooperating in a leaktight manner, in the protection position, with said ball (104) of the syringe, said cavity (26) of said cap (20) being dimensioned in such a way that, when said guard (10) is removed from said syringe (100), said cavity (26) is connected to the atmosphere via said at least one slit (72) before said tip (P) of the needle (A) is connected to said cavity (26).Ensemble de distribution comportant une seringue (100) comprenant un corps (102) pourvu dune boule (104) supportant une aiguille (A) pourvue dune pointe (P), et un dispositif de protection amovible (10) pour aiguille de seringue, ledit dispositif de protection (10) comportant un capuchon élastique (20) qui définit une cavité intérieure (26) délimitée par une paroi latérale (28) et par une paroi dextrémité distale (30), ladite paroi dextrémité (30) étant pleine et recevant de manière étanche, en position de protection, ladite pointe (P) de ladite aiguille (A) dune seringue (100), ladite paroi latérale (28) comportant un bourrelet annulaire (70) pourvu dau moins une fente (72) sétendant en direction longitudinale sur ledit bourrelet annulaire (70), ledit bourrelet annulaire (70) coopérant de manière étanche, en position de protection, avec ladite boule (104) de la seringue, ladite cavité (26) dudit capuchon (20) étant dimensionnée de telle sorte que
