Abstract: A device (1) for execution of overcasting seams comprises two needles (3, 4) carrying respective sewing threads, two support arms (6, 9) on each of which two lower (7, 8) and upper (10, 11) loopers respectively, are mounted. The loopers of each support arm (6, 9) interact with the loopers of the other arm (6, 9) and with the needles (3, 4) to form a first and a second overcasting seam portions superposed on each other. The invention also relates to a method to be put into practice by such a device (1), a needle plate to be installed on such a device (1) and a seam consequently obtainable therewith.