Abstract: An apparatus for X-ray analysis of materials advantageously utilizes a parabolic multilayer mirror for parallelizing the X-rays. Moreover, it may be desirable to monochromatize the parallelized radiation, for example by means of a crystal monochromator. According to the invention an influencing device for the X-rays is constructed as a single mechanical unit comprising a combination of an X-ray mirror (46) and a monochromator (48). This unit (66) can be arranged in the analysis apparatus in at least two positions (74, 76) in such a manner that the X-rays travel via the X-ray mirror (46) and the monochromator (48) in the first position (74) whereas the X-rays travel only via the X-ray mirror (46) in the second position (76). Consequently, no separate units comprising only an X-ray mirror or a combination of an X-ray mirror and a monochromator are required, so that a substantial saving in costs is achieved.