Abstract: The subject of the invention is a method for butt welding at least two metal sheets of different thicknesses, by means of a laser beam. The method consists in bringing the metal sheets into contact at their lateral faces to be butt jointed, in directing the laser beam towards the thicker metal sheet so that the vertical axis X--X passing through the focal point P of the laser beam on the said metal sheet is at a defined distance from the joint plane of the metal sheets and in making a welded joint at the butt jointed lateral faces by local melting of the said metal sheets by means of a laser beam.