A heel unit for a downhill or a combined downhill and alpine touring ski binding has a vertical-release functional group with a tensioning device with a first spring assembly for holding a ski boot downhill, and a horizontal-release functional group with a base plate to be positioned on the ski and a slide that deflects laterally opposing the ski longitudinal direction against the force of a second spring assembly, on which the vertical-release functional group is arranged, as well as with a compression spring assembly acting on the horizontal-release functional group. The vertical-release functional group rotates on the horizontal-release functional group around an axis running vertically towards the top of the ski or towards the vertical, such that, after a limited lateral deflection of the slide, the vertical-release functional group rotates against the force of the second spring assembly to release of the ski boot into the respective lateral-release direction.