This work aims to develop a process of ultrafiltration in diafiltration mode to concentrate the fraction of white wine polysaccharides of high molecular weight (arabinogalactan-proteins and mannoproteins) and to purify this fraction in terms of polyphenols, organic acids, and minerals removal. The membrane ETNA 10PP from AlfaLaval was characterized by an hydraulic permeability, Lp, of 105 L/(h.m(2).bar) and a molecular weight cutoff, MWCO, of 17 kDa. A membrane surface area of 0.036 m(2) was installed in a Lab-Unit M20 from Alva Laval. The permeation operating conditions, in total recirculation mode, were a temperature of 25 degrees C, pressures ranging from 0.5 to 5 bar, and an average velocity of 0.94 m/s. The ultrafiltration in concentration mode was run up to concentration factors of 4.25, and when diafiltration was introduced the concentration factors went up to 6.3. The permeate fluxes were maintained at an average value of 58 L/(h.m(2)).