Abstract: A syringe fitted with a clamping device for the needle and with means to enable the needle to be automatically retractable into the syringe body at the end of an injection comprises: outer and inner cylinders; openings at the ends of the outer cylinder; a third opening at an end of said inner cylinder; closing means for said third opening; a needle with a head; sealing means in said closing means; a first spring to push said needle against said closing means; a clamping device loaded by a second spring to maintain outward said syringe and to release said needle; a diaphragm in said closing means which bends before its breaking; a sharp element to break said diaphragm; closing means to prevent said needle from being reached and stopping means to prevent said second cylinder from being moved outward said syringe after its use.