This invention relates to an injection device for delivering a medicament to the human or animal body, in particular, but not exclusively, to a device having a replaceable medicament cartridge, including an auto-injector,wherein the injector device comprises: a housing a piston rod for driving a bung of a medicament container a drive mechanism including a motor for providing an output drive to the piston rod for delivering the medicament and control means for controlling operation of the device.
