An injection device comprising: a housing adapted to receive a syringe having a discharge nozzle, the housing including means for biasing the syringe from an extended position in which the discharge nozzle extends from the housing to a retracted position in which the discharge nozzle is contained within the housing; an actuator; first and second drive elements (232, 234), of which the first is acted upon by the actuator and in turn acts upon the second, the second acting upon the syringe to discharge its contents through the discharge nozzle, the first drive element being capable of movement relative to the second when the first is acted upon by the actuator and the second is restrained by the syringe; and of the actuator and the first drive element, one comprises a flexible arm that is biased toward a position at which it engages with a drive surface on the other, allowing the actuator to act upon the first drive element and preventing the former from moving relative to the latter, the flexible arm being movable against its bias under the action of the actuator to disengage the flexible arm from the drive surface; characterised in that: the second drive element comprises a stop that prevents the flexible arm disengaging from the drive surface until the first drive element has been advanced to a nominal release position relative to the second drive element, whereupon the flexible arm disengages from the drive surface, allowing the actuator to move relative to the first drive element and thus releasing the syringe from the action of the actuator, whereupon the biasing means restores the syringe to its retracted position. a housing adapted to receive a syringe having a discharge nozzle, the housing including means for biasing the syringe from an extended position in which the discharge nozzle extends from the housing to a retracted position in which the discharge nozzle is contained within the housing; an actuator; first and second drive elements (232, 234), of which the first is acted upon by the actuator and in turn acts upon the second, the second acting upon the syringe to discharge its contents through the discharge nozzle, the first drive element being capable of movement relative to the second when the first is acted upon by the actuator and the second is restrained by the syringe; and of the actuator and the first drive element, one comprises a flexible arm that is biased toward a position at which it engages with a drive surface on the other, allowing the actuator to act upon the first drive element and preventing the former from moving relative to the latter, the flexible arm being movable against its bias under the action of the actuator to disengage the flexible arm from the drive surface; characterised in that: the second drive element comprises a stop that prevents the flexible arm disengaging from the drive surface until the first drive element has been advanced to a nominal release position relative to the second drive element, whereupon the flexible arm disengages from the drive surface, allowing the actuator to move relative to the first drive element and thus releasing the syringe from the action of the actuator, whereupon the biasing means restores the syringe to its retracted position.