Injection device (30) comprises a housing (42, 52), a container for holding an injection fluid (32), a device for pressing the fluid from the container, a dosing unit (66) which twists relative to the housing and interacts with the outer thread of the pressing device and a coupling arrangement for stopping the first device from rotating relative to the housing (52) during the injection process. Preferred Features: The dosing unit and the pressing device do not twist relative to each other during pre-selection of the injection dose.