Ultrafiltration membranes with "self-cleaning" ability are presented in this work. Porous asymmetric membranes were formed by the phase inversion method from one-to-one blends of polysulfone and its aminated derivative. The characteristics of trypsin immobilized by static and dynamic sorption with cross-linking by glutaraldehyde was carried out using N-alpha-benzoil-L-arginine ethyl ester (BAEE). The self-cleaning properties are demonstrated in experiments where proteolytic membranes were used for concentration of casein solution. The essential improvement of ultrafiltration flux can be observed as a result of hydrolysis of protein blocking membrane pores.