Abstract: A syringe assembly has a syringe body adapted to be filled with an injectable liquid and having an annular neck defining an axis forming an axially outwardly open outlet and a needle insert fitting in and blocking the outlet and formed with an axially throughgoing passage so that a needle can be inserted axially through the passage of the insert into the body. A retaining collar engaged around the neck holds the insert in the outlet and a plug engaged in the passage fits over the retaining collar. A retaining ring fixed around the collar at the neck holds the collar on the neck and has an annular and axially outwardly directed end edge. A cup-shaped safety cap bearing axially inward on the plug has an annular and axially inwardly directed end edge confronting the retaining-ring edge and spaced axially therefrom by a gap which is bridged by a plurality of angularly spaced frangible webs unitarily formed with the ring and with the cap and extending from the cap edge to the ring edge.