An injection device is for use with a syringe having a bore extending from an end surface, a needle communicating with the bore through the end surface and a dispensing piston movable in the bore towards the end surface. The injection device includes a housing having an opening, a resilient member for biasing the syringe and needle inwardly of the housing, a drive element movable towards the one end so as to move the needle out of the opening against the bias of the resilient member, a delatch mechanism operable to release the syringe such that the needle moves inwardly of the housing, and a drive coupling. The drive coupling gradually reduces in length such that, after the drive element has moved the dispensing piston to the end surface, the drive element continues to move to the dispensing piston at the end surface.