A mammography unit having a mounting arm, on which a mounting for at least two X-ray receivers is rotatably disposed in such a way that one X-ray receiver at a time is positioned in an examination position inside an intended X-radiation field, while other X-ray receivers each remain in a reserve position outside the X-radiation field, is provided. The at least one reserve position is disposed on a side located in the X-radiation direction, relative to the mounting arm. In the case of two X-ray receivers, the X-ray receivers each form a lateral angle of between 45° and 90° with the axis of rotation of the mounting. By using a releasable connection of the mounting to the mammography unit, high modularity is provided.