The aim of the work was to determine the effect of using a cellulose nitrate membrane (CN) for purifying diffusion juice and to compare the content of some components and features of diffusion juice before and after purification. The question was investigated as to whether the membrane filtration process could replace the traditional liming and carbonation methods since the outcome of juice purification depends on its quality. The end result of the purification of good quality diffusion juices when using a cellulose nitrate membrane was 34.8-41.4% and was thus comparable with the traditional method. The application of membrane filtration made it possible to purify juice of bad quality, which could not otherwise be purified under industrial conditions, the purification effect being about 13.1-15.6%. In juices filtered with a cellulose acetate membrane, the content of sucrose and reducing sugars hardly changes. The viscosity of filtered juices decreased by 0.9-1.9 mPas and was close to that of pure sucrose solutions of the same concentration. The content of a-amino-acid nitrogen, after filtering the membrane, decreased by 12% to 34%. The higher the purity and the lower the viscosity of the diffusion juice, the greater was the permeate flux.