A protection device for a syringe needle, having an elastomeric cap. The cap defining a housing receiving the distal portion of the body of a needle syringe. An end wall of the cap perforatable over a fraction of its thickness by the free end of the needle. The housing having a first segment of frustoconical or cylindrical shape； a cylindrical second segment for housing the distal portion of the syringe body that carries the needle, and a third segment that tapers from the second segment towards the end wall of the housing, the lateral wall provided with an annular bead arranged in the housing, at least one slot extending in a longitudinal direction across the annular bead. The second segment includes at least one axial groove that extends longitudinally over a fraction of the height of the second segment.
