An autoinjector comprises front and rear separable housing parts 10, 12. These are connected by a rotary coupling action such as by bayonet coupling and the relative rotation action turns a needle shield 20 from a locked position in which it is both locked against longitudinal movement and acts as a shutter obscuring the contents of the syringe to an open position where the contents of the syringe are visible and the shield portion is freed for longitudinal movement. Connecting and securing the rear portion 12 on the front portion 11 therefore unlocks the needle shield 20 for operation. On completion of an injection, uncoupling of the front and rear portions returns the needle shield 20 to its locked position so the front portion may be disposed of safely.
