In a method for insulating a coil winding of an active part of a rotating electric machine, the active part is impregnated with an insulating resin in a tub-like impregnation container by vacuum pressure impregnation. The active part is held in the impregnation container, after impregnation with the insulating resin, completely submerged in the insulating resin. The impregnation container together with the active part is introduced into a baking oven, and the active part is set in the insulating resin in rotation about a longitudinal axis of the active part. While the active part is rotating, the insulating resin is purged from the impregnation container and then the oven temperature is increased to a predetermined baking temperature which is maintained for a predetermined baking period. Rotation of the active part is terminated after expiration of the baking period.