The aim of this work is to analyze the sources of errors inherent to the residual stress measurement process by X-ray diffraction technique making an interlaboratory comparison to verify the reproducibility of the measurements. For this work were machined specimens with grinding finish, with polishing finish and to be a reference standard an iron powder was used To verify the deviations caused by the equipment, those specimens were positioned and with the same analysis condition, seven measurements were carried. To verify sample positioning errors, seven measurements were performed by positioning the sample at each measurement. To check geometry errors, measurements were repeated for the geometry Bragg Brentano and Parallel Beams. In order to verify the reproducibility of the method, the measurements were performed in two different laboratories and equipments. The results were statistically worked out and the quantification the type A errors that suggests that is a significant difference between the methods and orientation of grooves directions.