Abstract: Non-reusable syringe having a syringe body, a hypodermic needle and a slidable piston for drawing and discharging fluid through the needle. In one embodiment, the non-reusable syringe includes a movable engagement member. A first position of the movable engagement member permits initial withdrawal of the piston, allowing fluid to be drawn into the syringe. Initial withdrawal of the piston moves the movable engagement member into a second position. After the fluid has been substantially discharged, the second position of the movable engagement member captures the piston and prevents the piston from being withdrawn again. In another embodiment, the movable engagement member is mounted on, and movable with respect to, the piston. The non-reusable syringe can also include a releasable connection between the piston and the piston driver. Once the piston has been captured, a second attempt to use the syringe will separate the piston from the piston driver, further preventing reuse of the syringe.