To develop new hemopurification systems based on cellulose membrane, we synthesized a graft copolymer of cellulose with poly(2-methacryloyloxyethyl phosphorylcholine) (MPC) by a metal-catalyzed atom transfer radical polymerization process in homogeneous media. First, cellulose was dissolved in a DMAc/LiCl solution system, and it reacted with 2-bromoisobutyloyl bromide to produce macroinitiator (cell-BiB). Then, MPC was polymerized to the cellulose backbone in a homogeneous DMSO/methanol mixture solution in the presence of cell-BiB. Characterization with FT-IR, NMR, and GPC measurements showed that there obtained a graft copolymer of cellulose backbone and poly(MPC) side chains (cell-PMPC) with well-defined structure, indicating a controlled/"living" radical polymerization. The proteins adsorption studies showed that cellulose membranes modified by the as-prepared cell-PMPC owns good protein adsorption resistance. (C) 2008 Wiley Periodicals, Inc.