Abstract: Known high-pressure spray nozzles tend to develop wear at outlet edges for a flat stream because of fluid emerging at very high pressure. It has already been proposed to provide, on the nozzle bodies, instead of transverse continuous outwardly open groove-shaped cuts, outlet channels with a cross-sectional pattern that expands outward trumpetwise in an elliptical shape or to prevent any contact between the nozzle body and the high-pressure stream at the outlet edge. It is now proposed to provide the outlet channel with an elliptical cross section, with expansion of the cross section exclusively in the direction of the major semiaxis but with no increase in dimension in the direction of the minor semiaxis. In this way, the flat stream to be formed can be guided and held together without wear at an outlet edge. The nozzle can be used as a high-pressure flat stream nozzle for de-scaling.