Surface-initiated atom transfer radical polymerization (ATRP) was used to tailor the functionalilty of polysulfone (PSF) membranes. A simple one-step method for the chloromethylation of PSF under mild conditions was used to introduce surface benzyl chloride groups as active ATRP initiators. Covalently tethered hydrophilic polymer brushes of poly(ethylene glycol)monomethacrylate and 2-hydroxyethyl methacrylate late and their block copolymer brushes were prepared via surface-initiated ATRP from the chloromethylated PSF surfaces. A kinetic study revealed that the chain growth from the membranes was consistent with a controlled process. X-ray photoelectron spectroscopy was used to characterize the surface-modified membrane after each modification stage. Protein adsorption experiments revealed substantial antifouling properties of the grafted PSF membranes in comparison with the those of the pristine PSF surface. (c) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 1942-1946, 2009