Abstract: A method for adjusting the primary side of an X-ray diffractometer wherein the primary side comprises a collimator, an X-ray optics, an X-ray source, in particular an X-ray tube, wherein the collimator, the X-ray optics and the X-ray source are mounted directly or indirectly on a base structure, and wherein the orientation and position of the X-ray optics and the position of the X-ray source are adjusted relative to the base structure, is characterized in that the orientation and position of the X-ray optics and the position of the X-ray tube relative to the base structure are measured and set at predetermined target values, so that with these set target values, X-ray radiation emanating from the X-ray source and conditioned by the X-ray optics is detectable at the output end of the collimator.