An attempt was made to predict the length of dry hides on the basis of body mass at the age of 12, 16 and 20 weeks, the body mass during the Autumn assessment /licence/, after slaughter, and the mass and length of humid hides of 74 males and 56 females of polar foxes. The authors indicated the influence of the litter, the origin and sex on the shaping of all examined characteristics of the animals and the influence of the time of birth on the body mass of 12 weeks old males and females and the mass of humid hides of females. Of the greatest cognitive value were equations assessing the length of dry hides made on the basis of measurements of body mass and the mass and length of humid hides. Although these equations were very exact they were of little practical value since they could not be used in the assessment of live animals. The exactness of equations assessing the length of dry hides only on the basis of measurements of body mass did not exceed of 74% accuracy of equations considering the body mass and the mass and length of humid hides. Such equations may be useful in practice because the standard error in assessing these equations does not exceed 3.0-3.2% of the length of dry hides. Measuring the body mass of 20 week-old males and measurements of the body mass of females during the Autumn licence made on the basis of live characteristics have been of the greatest significance in assessing the length of hides.