The influence of the weight and the freshness of the skin, the temperature and duration of the liming process, and the concentration and amount of the liming solution showed that the total N and the amide N content decreased with the degradation of the skin substance as well as with an increase in the duration and time of the liming.The digestibility of the collagen by trypsin was proportional to the degradation, while the Cr fixation by the skin increased with the duration of liming and with the temperatureIn pure Ca(OH)2 liming solution, the total N and the amide N were not influenced by the Ca(OH)2 concentration nor by the amount of liming solutionThe total N and the amide N in Ca(OH)2-liming solutions to which Na2S had been added were affected by the Ca(OH)2 concentration