The invention is directed to an immersion nozzle for a metallurgic vessel arranged upstream of a casting device, in particular a continuous casting mold or a twin roller, in which a slit-shaped pour-out opening (2) having a length that is several times greater than its width is provided in the base area. The cross section widens in the direction of its mouth from a round inlet cross section to a mouth cross section whose one semiaxis is smaller than, and whose other semiaxis extending perpendicular thereto is greater than, the semiaxis of the round inlet cross section and whose base shape corresponds to that of the body of revolution of an ellipse or of an oval mouth cross section around the greater semiaxis, and the slit-shaped outlet opening extends in direction of the greater semiaxis.