In the following degree is a discussion of hard protective coatings for milling of hard heat improved steal with hardness off 55 HRC. The main problem in milling of hard heat improved steal is the wear of the cutting tools. Because of different influences at first, we get high roughness of the surface, in the next moment the dimensions of the workpiece are not in tolerances. We must change the tool or sharpen it. To protect tools from wear we need to develop new protective coatings. Our goal in the degree is to find out which protective coating from test is the most appropriate for milling our workpiece material. The results will give us good information’s for the developing coatings in the future. We made the test in which we tested different coatings. At the end, we compared the wear resistance of the tools and shape of the chips. From results, we can see that the best protective coating for milling of hard heat improved steal is TiAlSiN coating.