The Barkhausen noise technique was used to characterize machined surfaces of small diameter tensile specimens. The Barkhausen noise butterfly curves measured for specimens with different surface finishing (grinding, lathe working) at several different analyzing frequencies were compared to those obtained on electro‐polished specimens. Microstructure modifications at the surface by machining are the reason for a complex structure of the butterfly curves, especially, those achieved at high analyzing frequencies. A new analyzing technique was developed based on cross correlation of a Barkhausen noise butterfly curve with a curve of a reference material. Depth profiling results achieved by this method showed excellent agreement with x‐ray diffraction measurements. © 2003 American Institute of Physics