Abstract: A device for closing an opening (12) performed in the sternum during heart surgery and for fixing the breast bone halves (13, 14) in relation to each other is described, said device consisting of (a) a plate (1) comprising two flat, longitudinal, parallel anchoring members (2, 3), which are spaced a distance from each other and provided with through-holes (11), and spaced apart, transverse, flat connection pieces (4, 5, 6) which are connected to the anchoring members to form a rigid unit therewith, and (b) a plurality of attachment wires (15) to be inserted into the breast bone halves from below and into said holes (11), the pairs of end portions of said attachment wires being twisted together to the plate.