A questionnaire was designed to give seven subjective degrees of monotony with other data concerning objective characteristics of the work. The questionnaire was used in plants with similar technology. It could be shown that the criterion of duration of the operation itself is not sufficient for classification of degrees of monotony. It is necessary to add data concerning the structure of operation. Non-technical and organisational factors in production—age, length of time on job, etc.—can affect the degree of monotony, but are not of primary importance. The paper also deals with the subjective aspects of monotony and the opportunity for the employee to change operations.