The subject of the invention is the fastening of a sealing bellows to the joint housing of a ball joint, in which the housing-side rim of the sealing bellows is laid firmly into a ring groove circumscribing the joint housing, designed substantially U-shaped in cross section, the bellows rim having a profiling adapted to the U-shape of the ring above and being pressed into the ring groove by a clamp ring. To increase the sealing effect, it is proposed that the profiled zone of the bellows rim lying opposite the bottom of the ring groove forms, when drawn on by the tension ring, a fold lifting off from the bottom of the groove, arched upward, which stretches under the pressure of the clamp ring to force the bellows rim against the side walls of the groove.