The purpose of the research conducted in the laboratory is to study the basic regularities of the ultrafiltration process of microfiltration permeate of skim milk, called native whey (NW). The objects of the research are NW, its ultrafiltration process and the obtained ultrafiltration retentate, NW permeate. To create the initial information base of the research work we used the results of the analysis of literature data from the libraries of the Russian State Library, North Caucasus Federal University, as well as the global network of the Internet and so on. Physicochemical characteristics of NW, as an object of ultrafiltration, were determined according to standard methods and on certified equipment. The main operating modes of the NW ultrafiltration process were determined experimentally. A mathematical expression allowing to quantitatively determine the permeability of ultrafiltration membrane depending on the working pressure, flow rate of circulation and temperature of the separated system was obtained. Quantitative indices of casein and whey proteins content in the resulting ultrafiltration retentate and permeate were determined. The results of the experimental research stage are the basis for the preparation of recommendations on the technology of ultrafiltration of NW with the use of pilot baromembrane equipment in industrial conditions. The obtained experimental data can be used as initial information for nanofiltration of ultrafiltration permeate. The field of application of the results is dairy industry.