There is a dense poly(2-dimethylamino ethyl methacrylate) (PDMAEMA) layer on the surface of poly(acrylonitrile and 2-dimethylamino ethyl methacrylate) (PAN-DMAEMA) membrane. The contact angle measurement indicated that the hydrophilicity of membrane increases at higher pH value and ionic strength. The reorientation of PDMAEMA after environment stimuli results in further enrichment of ester groups on the membrane surface according to XPS analysis. The amount of adsorbed bovine serum albumin (BSA) on PAN-DMAEMA membrane is dramatically decreased at higher pH value and ionic strength. A viewpoint based on the minimizing electrostatic interactions between PDMAEMA groups after environment stimuli leading to the conformation switch of PDMAEMA chains from stretched to shrunk states, which results in higher surface enrichment of ester groups enhancing hydrophilic property of the PAN-DMAEMA membrane, was put forward to explain the resistance of protein adsorption on the membrane. (C) 2007 Published by Elsevier Inc.