Abstract: Injection syringe of disposable type, including a cylinder (91), in which a piston is displaceable in and out respectively, a piston rod (3) having a press plate (12), and an injection needle (4) at the end of the syringe cylinder (1). The syringe needle (4) is mounted from inside the syringe cylinder (1) and is releasably connected (5, 9) to the syringe cylinder (1). The syringe needle (4) or the carrier (5) thereof is formed with one or more blocking ratchets (6) which cooperate with the syringe piston (2) or the piston rod (3), and which blocks the piston against being retracted after the sole injection is made, so that the syringe needle (4) becomes retracted into the inner of the syringe cylinder (1) upon withdrawal of the piston (2) after the injection has taken place.