A needle assembly 1 comprises a needle 90 which is secured in a main body 10 configured to be removably attached to an injection device in use, and has a forward portion which projects forwardly from the main body. A shield 50 is slidably mounted within the main body 10 and an actuator portion 70 extends outside the main body and is configured for pushing the shield 50 forward manually in use. The shield 50 is slideably moveable between a first position in which the forward portion of the needle 90 projects forwardly of a shield cavity 64, and a second position in which said forward portion of the needle is located within the shield cavity 64. The shield 50 and main body 10 are provided with cooperating features comprising at least one latching element 66 such as resilient legs provided on one of the shield 50 or the main body 10 and at least one corresponding engagement feature 44 such as protrusions provided on the other of the shield 50 and the main body to lock the shield in its shielding position.
