Abstract: Procedure based on X-ray diffraction for measuring the stress state of metals, in particular austenitic steels. In the procedure the detector surface (10) is inclined about an axis (A--A) lying on the surface of the sample (20) being examined which is substantially perpendicular to the direction of the stresses (.sigma..sub.xx) being examined. By means of the detector surface (10) the diameters (2S.sub.ax) of the so-called Debye rings in the direction of the surface being examined are recorded at two or several inclination angles (.psi.). The detector surface (10) has arcuate shape, as viewed in the direction (B--B) at right angles against the inclination axis (A--A), and in the procedure is used such as arcuate detector surface (10) elongated in the direction of said inclination axis (A--A) and narrow enough in the opposite direction that an inclination angle (.psi.) of the detector surface (10) large enough in view of the procedure's implementation is feasible.