Surface modification of membranes is thought to be equally important to the membrane industry as membrane material and process development; surface functionalization has already become a key technology, the major aims being performance improvement (flux and selectivity) by reduction of unwanted protein fouling (often considered the first step for biofouling). Poly(arylsulfone) [i.e., Polysulfone (PSO and poly(ethersulfone) (PES)] membranes have been widely used for separation and purification purposes. However, in many cases, nonspecific (protein) adsorption takes place on the membrane surface and in the membrane pores due to the inherent hydrophobic characteristics of poly (arylsulfone). Therefore several (surface) modification techniques for poly(arylsulfone) membranes have been developed. Given the importance of modification methods for these membranes and their operation, we decided to dedicate this mini-review solely to this topic. The modification methods can be divided into the following main groups: (1) coating, (2) blending, (3) composite, (4) chemical, (5) grafting, or (6) a combination of methods. With all these methods. interesting results were obtained concerning reduction of protein adsorption (see respective sections), although the quantification of improved performance is not straightforward. In the Section 4, all techniques are compared on various aspects such as flux after modification, simplicity, reproducibility, environmental aspects, and cost effectiveness. (C) 2011 Elsevier By. All rights reserved.