Abstract The study of interrelation between kinetics of protein adsorption and flux of water through ultrafiltration membranes is of interest for understanding the influence of adsorption on ultrafiltration. A short model sketch of protein adsorption derived from complicated transport phenomena is presented. As quantitative criterion of protein adsorption the ratio of reversibility is proposed. This ratio describes the relative amount of adsorbed proteins that are reversibly arranged on the polymer surface. Ratio reversibility depends on chemical structure of membranes in sequence: polysulfone < polysulfoneamide (33% amide groups) < polysulfoneamide (47% amide groups) < aromatic polyamide. It is shown that protein adsorption mainly contributes to the deterioration of the water transport.