A safety needle assembly comprising: a hub which includes a proximal end for connection to a syringe and a distal end; a cannula including a proximal end connected to the distal end of the hub, the cannula also including a lumen extending therethrough and a distal end; a collar formed separately from the hub and mounted on the hub, the collar being rotationally fixed on the hub and including a sheath mounting portion; a protector positioned over the cannula and covering the distal end of the cannula, the protector being removable to expose the cannula including the distal end; a sheath provided with an opening extending along at least a portion of a longitudinal extent of the sheath, the sheath being positioned outside the protector when the protector is positioned over the cannula, the sheath being pivotally connected to the sheath mounting portion of the collar to be pivoted, after removal of the protector to expose the cannula, towards the cannula so that the cannula passes through the opening in the sheath and is covered by the sheath, characterised in that the hub possesses an outer surface provided with two spaced apart sets of outwardly extending projections (30, 32) each extending over less than one-half of a circumferential extent of the outer surface of the hub, the collar including an inner surface provided with a plurality of inwardly extending projections, the inwardly extending projections engaging the outwardly extending projections (30, 32) in each set to rotationally fix the collar on the hub, and the hub includes an annular recessed region located distally of the projections (30, 32) on the hub, the collar including an inwardly directed annular ridge positioned distally of the projections on the collar, the inwardly directed annular ridge on the collar being positioned in the annular recessed region on the hub. a hub which includes a proximal end for connection to a syringe and a distal end; a cannula including a proximal end connected to the distal end of the hub, the cannula also including a lumen extending therethrough and a distal end; a collar formed separately from the hub and mounted on the hub, the collar being rotationally fixed on the hub and including a sheath mounting portion; a protector positioned over the cannula and covering the distal end of the cannula, the protector being removable to expose the cannula including the distal end; a sheath provided with an opening extending along at least a portion of a longitudinal extent of the sheath, the sheath being positioned outside the protector when the protector is positioned over the cannula, the sheath being pivotally connected to the sheath mounting portion of the collar to be pivoted, after removal of the protector to expose the cannula, towards the cannula so that the cannula passes through the opening in the sheath and is covered by the sheath, characterised in that the hub possesses an outer surface provided with two spaced apart sets of outwardly extending projections (30, 32) each extending over less than one-half of a circumferential extent of the outer surface of the hub, the collar including an inner surface provided with a plurality of inwardly extending projections, the inwardly extending projections engaging the outwardly extending projections (30, 32) in each set to rotationally fix the collar on the hub, and the hub includes an annular recessed region located distally of the projections (30, 32) on the hub, the collar including an inwardly directed annular ridge positioned distally of the projections on the collar, the inwardly directed annular ridge on the collar being positioned in the annular recessed region on the hub.