The invention relates to a method for monitoring the bending of a shaft, particularly a shaft in a mixing kneader, the shaft having a bearing at least on one side. In a first step, the deviation of the shaft from the radial position is measured on at least one position different from the bearing of the shaft. In a further step, a reference value is optionally determined from the measured deviation from the radial position. In a third step, the deviation from the radial position as measured in the first step or the reference value found in the second step is compared with a predetermined limit value.