Abstract: A method for controlling access of a computer to user data that are stored in a memory device includes calling up structure data of the memory device, by means of a BIOS, and accessing the user data on the basis of the structure data. The structure data are only transmitted to the BIOS after authentication of a user. There is a control device for controlling access to user data. Structure data of the memory device can be called up by a controller, on the basis of which the user data are accessible. A user can be authenticated upon a request for the structure data and transmission of the structure data is controlled by the control device. When a request for structure data is issued, an authentication routine for authenticating the user is first transmitted by the control device to the BIOS, and carried out on the computer.