Abstract: The invention relates to a method for dressing of a multiple thread grinding worm, wherein the contour of the flanks of the screw channels which are running spiral-like and parallel to another is produced by a dressing tool. To obtain an improved grinding result especially with reduced dressing time the invention proposes that in at least two screw channels contours of the flanks are produced, which are distinguished from another by their geometry and/or by their surface structure. Furthermore, the invention relates to a method for grinding of a work piece and a grinding worm.