The invention relates to a method for operating a bale opener (10) with at least one milling drum (12). By rotating the at least one milling drum (12) about an axis of rotation and by moving same along a predetermined travel path (sv) at an acute or right-angle to the axis of rotation, the bale opener (10) is in a position to mill a fibre bale (2-6), whereby fibrous material is removed from the fibre bales (2-6). The method comprises a starting step (S2) in which it is detected whether there is an overload at one or all of the monitored at least one milling drum (12). In the event that an overload is detected, the method proceeds to a determining step (S3) in which the presence of a overload status is determined. This is achieved if the detected overload occurs continuously along a path covered by the at least one monitored milling drum (12). In the event that the presence of an overload status of this type is determined, the method proceeds to a triggering step (S4) involving the triggering of an overload reaction. In addition, a bale opener (10) is provided which is provided with an at least one milling drum (12) of this type. The bale opener (10) is configured to be operated according to said method.