Abstract: A nonrefillable syringe including a unique plunger stem/piston arrangement which is designed to disconnect after an injection has been completed. A piston is removably connected to a plunger stem by a first connecting member and a novel nipple assembly. The first connecting member comprises a plurality of circumferentially spaced arms extending longitudinally away from the piston and forming an interior aperture. The nipple assembly includes a tapered nipple removably matable with the aperture formed by the circumferentially spaced arms of the first connecting member, and a cylindrical carrier for slidably positioning the nipple assembly within a hollow end of the plunger stem. The tapered nipple is gradually forced out of the aperture during use of the syringe. When the tapered nipple is forced completely out of the aperture, the piston disconnects from the plunger stem.